No two people with AS are the same, we just have the same neurological condition that can manifest in a myriad of different ways. Whether or not he enjoys being nasty is down to his personality not his AS. I suspect that you don't understand AS as well as you think you do. I would guess that he became overwhelmed by your attention and, most of the time, had no real idea what your intentions, beliefs, values etc were (as well as being unclear himself what he was feeling about things) and, as a result, his frustration at himself for not "getting it" and his frustration at you for thinking that you have a handle on AS and, consequently, him may have been vented as anger or nastiness.
Being with someone too saintly can put pressure on anyone but especially those who do have to deal with the fact that they go around upsetting people they rather wouldn't - it can feel too uneven.
It is tempting to see bad behaviour as the "real" person because that's what NTs are like - when the mask slips you see the person inside. With AS it's different - many of us have a hard time knowing what we think or feel about something and, often, the more important or pressing the issue the more frustration can lead to a sort of mini-meltdown where the negativity inside has to come out and can be misinterpreted (usually with good reason) as an attack.
I have similar problems with women. There is a certain type of woman who tells me she totally gets AS and that I should be delighted at having met such an enlightened soul. Sadly, in may case at least, they are just deluding themselves because they like me for the more everyday reasons - I am clever, not unattractive and single. I feel like I am protecting them from themselves because, despite how charming I can be, I absolutely need down time and I WILL make mistakes which can come across as arrogant or insulting whether she cares to believe it or not. Very few women, in reality, are prepared for a relationship where one person's emotional needs are so at odds with the other.
Bottom line is this - relationships, hard as they are for NTs, are much, much more difficult for people with AS and, as a result, the people who care for them. It's often not fun and can be one-sided. My guess is he feels just as bad as you but doesn't even know exactly why.
I am hoping to meet someone who is as crazy as me and who knows it so we both get to acknowledge our mutual efforts in respect of each other. The movie "Mozart and the Whale" deal with this, albeit in the context of an AS/AS relationship. May be worth a look.
Hope my ramblings made sense to you