He was just sharing his opinion, not trying to force it on you. The good thing about fan theories is that they aren't proven fact and you don't have to agree with them :)
One thing I wanted to say earlier but deleted for some reason was to consider the fact that Spongebob is a cartoon character, and he's probably not the only one to act this way. I mean, it is a cartoon, so characters are going to act like this once in a while. Real people can exhibit any of these characteristics at once as well, but it doesn't mean they have autism. But of course, that doesn't mean Spongebob doesn't have it either...