Hmm... personally I do not think Nonny is an autistic kid. He is just cautious. And I can tell you that because I had the same behavior when I was his age (And I do not have autism).
Some people, including kids, just like to be alone and this is just perfectly fine. The way I see it, he speaks only when he thinks he should. He speaks when he has something important to say (for example when he gives the definitions to some words the guppies don't know).
But then again I could be wrong, this is only my personal opinion.
But if you ask me if I think he's autistic... no, I do not think he's autistic, he's just shy.
I guess there are just speculations of Nonny having autism. Only the Bubble Guppies creator and crew know about Nonny.
Although I'm a loner myself (I don't know if I would be if I didn't have apserger's or any form of autism) I didn't always like being alone. In fact when I was 14, or starting before that, I had no one to hang out with outside of school. I mean I admit I was isolated, so my stepfather told me and insisted I played outside with the other kids, (I was more of an indoor person and tended to play indoors and by myself) but I did like having company including with other kids. But during the last of my middle school and throughout my high school years, I had no one to hang out with outside school, but my sister did. There were times I was shunned and excluded and I was annoying to others and I admit I can be annoying. But I wished I had someone to hang out with. I guess some of it is my fault.
Then again, maybe it was better I didn't, given the person I was and am now, and some of what I was I still am. I feel more comfortable alone than I do with other people, I mean I don't mind being with others but not too much, sometimes I can only take it in small doses if you know what I mean. Plus admittedly I'm hard to take and hard to put up with. And not just in person but online too, I could even be that way on this website, I know I am on other websites like Fairly Odd Parents Wiki, Deviant Art, Fanfiction.net, and Wrong Planet to name a few.
Bottom line, and I don't know if my having asperger's has even a little to do with it, but I like being a loner, mostly. I feel more comfortable that way. But there were times I wanted to be with others. Well, it's not just asperger's, I have other issues like but not limited to anxiety and depression, that too hinders my social life, although I also don't have a social life because I prefer not to have one. I also don't like hurting or upsetting others, but sadly it's inevitable.
To stay on subject, I don't know if Nonny is better than I am or not as good. Maybe he has autism, maybe he doesn't. Maybe he is socially awkward like I can be, maybe he's not. Maybe he has depression or anxiety, maybe he doesn't (don't quote me on that, that's just my personal imagination) but he is cautious so I've read and he's more cautious than I am! But he's not anti-social, (he doesn't hurt other people on purpose. Would an antisocial person be that nice to squirells? And would an antisocial person be nice enough to help clean a park? Well, some antisocial people hide that part of themselves and appear not to be.)
But I don't think Nonny's a bad kid and Alan's right, some people like to be alone and there's nothing wrong with it, well, if it's not done too much, we all need othe people, but some prefer to be alone and I'm one of those people.
To be honest, I talk to myself out loud a lot. Is that bad? I done since I was small and I can't stop. I mainly talk about my interest like animals and pokemon I also talk to myself when I have problems at school for example. I usually do it in my room, not in public. I'm. Not positive Nonny's autistic but he has some signs of autism, but like you said he could be just shy but then again why is he so smart? Other prediction of mine. Nonny kind of reminds me of a character in peppa pig. Edmond Elephant, one of George's friends and Emily (peppa' friend) little brother. One of all the toddler character he is the only one to speak in full sentences unlike Nonny though he is far more socialable and doesn't have trouble playing with others or smiling. Ferb from Phineas and Ferb is another character that reminds me of Nonny. Ferb barely speaks, doesn't smile much and is crazy smart. Some people say Phineas is also autistic but I don't think so. Ferb I'm positive he is autistic. I remember in your cartoon prediction you said Some people think Gil is autistic. I've seen a few websites where they say that but I honestly think he has more ADHD than aspergers.
Sorry I left you hanging, I visit this wikia on a limited basis so please try not to take it personal if you leave a message for me and I don;t get to it. I know this sounds ridiculous but for psychological purposes I visit this wikia very rarely and I'd rather not say why but I do like this wikia (this is for anyone reading this) and I do hesitate to come.
I talk to myself out loud a lot too, my mother can hear me! I've been talking to myself when I was little too, sometimes I've even self-bullied, if you know what I mean. Or was a self-tyrant. I too talk a lot about my interests, especially trains and railroad crossings, check my deviant art gallery (http//.willm3luvtrain.deviantart.com) and look at some of my fanfics on fanfiction.net, some stories and lots of pictures involving railroad crossings (although I'm yet to write a Bubble Guppies fanfic story including a railroad crossing and I plan to eventually, although there were a few shown in "Triple Track Train Race" and many many kudos to them for including that, in other words "Thank you very much Bubble Guppies crew for including that, not everyone does that!) But you see what I mean. I mean I'm not ashamed of my interests and you shouldn't be either depending on what they are and being interested in animals is okay and you can be interested in Pokemon too although I've lost much of my interest in Pokemon, Pokemon was a fad in my life once.
I know about Peppa Pig, I rarely watch the show but it's a nice show. I'm not half as crazy about it as I am Arthur although I might like it better than Olivia, who's also an anthropomorphic pig, but unlike Peppa and George, Ian seems to give Olivia a hard time (I haven't watched Olivia since 2012 or 2013 so my memory of them is dulled right now) I like that the girl rabbit's mother had a twin boy and girl, in addition to the boy rabbit younger than the girl who is Peppa's age but older than the twins. See? I know less about Peppa Pig than you do, and I've watched that since 2008 (back when it was a short and befor it became a series, I would watch it while watching 64 Zoo Lane, a cartoon I only like watching at night.) Peppa Pig also had a couple train episodes and one of them even came with a crossing gate as I like! But who other than me cares about that?
I'm not going to remember to do this but maybe I'll pay more attention to Edmond Elephant if I ever watch Peppa Pig again because I don't think I ever noticed much of him.
I agree about Ferb, it's almost like he's even a person, or not even alive or like he's inanimate, being as quiet as he is but he isn't passive. And he's not a robot or an alien. And I notice he doesn't smile much but I've seen him smile in more recent times. I do like it when he talks, I love his accent. I even like the way he sounded when he said of Buford "He was up in my face."
I never thought of Phineas being autistic and would doubt and deny that. Ferb being autistic is a little more believable to me.
I never said this to anyone yet and intended to but not until I was back on Deviant Art but Ice Bear from We Bare Bears is a lot like Ferb to me. (Ice Bear is also William's favorite character from We Bare Bears because Ice Bear's a polar bear and polar bears are William's favorite bears because they're white.) Okay in English, "My most favorite character is Ice Bear."
I would almost agree about Gil having ADHD given the guy he is (I'm just saying "given the guy he is") and a lot of the things he does and gets himself into. Oh, before I go on and so this isn't mistranslated by anyone, nobody with ADHD is bad. I don't think anybody is, I like people even if they have ADHD.
It's okay. I barely come on either. But anyways what you were saying about Arthur, I think it's very educational they even made an episode about autism (mainly aspergers). But like you I don't come on much either