Don't be so quick to jump to the AS conclusion,.
My son is 20 mths old, and we considered he may have AS as he was very much alike at that age as what you describe, didn't talk a lot and very happy in his own little world. He only started walking last week, and with me having AS, we figured it could have been inherited.
However after getting tests at 18 mths old) etc it was found to be a sensory processing issue with his ears, which affects balance, causes over sensitivity to loud noises etc. He prefers what we're eating to what he has, and to this day refuses to eat any sort of Pasta but loves Rice. Like your friend's son, he is also very smart, at 18mths was able to use the TV, find himself on my Cell Phone, and picked new things up incredibly quickly (was toilet trained at 11mths)
Really it just all clicked for him at some point, he's now happy, VERY talkative, happy to interact and always asking questions. Every child is different and I think sometimes us overprotective adults rush to find a label for any behaviour we see as non conformist.
Seek advise from a Paediatrician, they can refer you to specialists if need be. It "could" be an AS issue, but it could be that you yourself is suffering what they call "medical students syndrome", jumping immediately to the worst possible diagnosis.
Get it checked definately, and go from there.