we are all allowed to pick our friends. if you become uncomfortable around him, it would be "rude" of him to act in the way he is with you around, or with people you are also friends(or more) with... its not all one sided. so just because your parents seem to think you are being rude, it doesnt void him from being rude. (honestly i dont know what term "rude" exactly is defined as, but i do know its categorized as unfriendly).... and it could be percieved to be "rude" by tolerating him and continuing to lead him into thinking that your okay with his actions(just trying to add perceptions from many different angles).
but like a lot of people on the spectrum, it can be hard to read between the lines or seeing what others might be feeling or thinking. so he may not be good with reading others hints or cues. meaning the best approach with some on the spectrum is being direct(if something he is doing is causing distress, let him know what it is, and if you can identify why it distresses you, you might add that in. he may not even notice and give a second thought on the things hes doing. until you bring his attention to it and your point of view).
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disclaimer: there are quite a few "tapp-o"s while using my phone. if i dont recognize it, and if it doesnt seem to make sense, then the chances of it being a tapp-o (typo) are very high.
*currently using iPhone 4*