You might like to do some background research into autism - from a professional organisation - so you can better understand it. Most of what you say, is part of the 'condtion', so your strong judgements about him/it, aren't bringing any enlightenment to the picture. If anything, likely making it worse.
Austistics are a level of openness and innocence that ought to be emulated more often. Not the meltdowns - that's their wiring system on overload, but certainly the belief that a 'stranger is an unmet friend' is something we can embrace, instead of shun. Remember that developmentally, his brain isn't 11 y.o. It's at least 6 years younger.