Having problems with social communication and interaction doesn't mean they are incapable of knowing right from wrong. Particularly an older kid. They are not fucking stupid, in fact, often it's quite the opposite. One of my best buds' oldest son has autism, and he is a very good artist, and frankly an awesome kid to be around. Very well versed in history, particularly WWII.
It's not a free pass to do anything they fucking feel like and get away with it. Just as with anyone, their support system and parenting, or lack thereof can have a major impact on their behavior. This kid's behavior is unacceptable for his age, autism or not, and there is not an autism expert in the world that would disagree. Does it give him a little leeway? Maybe, but it is not an outright excuse.
If he kills someone, do we just shrug it off, cuz he's autistic? Of course not. Might he get a lighter sentence? Possibly. But he would still be punished.