He might be or he might have other issues which makes him a bit different. Aspergers (high functioning autism) is a very hard thing to diagnose because of how similar the symptoms are to other disorders. I wish there was a one essay read on how people with autism communicate differently but the truth is we all have different ways of coping and thus different ways of communicating.
One of the big component to autism is this lack of understanding nonverbal communication. I've read up to 90% of communication can be done without using actual words so when there isn't an intuitive understanding of it, we're going to have social deficits. Some of us are better at compensating than others, I have a very high IQ and am very aware of the gaps in my communication so I have to play Sherlock Holmes when I have a conversation. With all things considering, I've gotten pretty damn good at it. I'm nowhere near perfect but most people wouldn't think I'm on the spectrum.
I don't have any of those behaviors (except how sarcasm can go over my head) that you described your classmate as having and from what you said, I don't think he has a form of autism. I could be dead wrong but those are not behaviors seen by everyone on the spectrum.
The best way to communicate with us aspies is to avoid what causes us confusions. We tend to be very literal and mostly pay attention to just the words in a conversation. It's not always easy to tell if someone is joking by their tone of voice or by how things are said. It's nearly impossible for me to look at someone and understand how they're feeling without any other context of the situation so it is much appreciated when people literally tell me how they are feeling.
I like to be treated like everyone else, I like making jokes and being the butt of jokes. When people make their intentions clear I can react better. Conversations are very confrontational for me, imagine only being able to read the text messages of what is being said, (written comunication has nonverbal components but we'll ignore that for now) Jokes and sarcasm are hard to convey without an lol or jk. Sometimes I need those social clues to be verbalize in order to pick up on them. Just please be kind when you do! After years and years of dealing with people getting angry at me for something I misinterpreted, it's not always easy to take criticism because it brings up a fuck ton of painful memories.
Oh yeah, one more important thing, I'm severely affected by something called sensory overload. I can be hypersensitive to any of my senses and it can make communicating impossible. Sensory overload over rides my cognitive ability and I'm not able to play Sherlock Holmes in conversations. It doesn't matter how nice someone tries to be, some days I absolutely can't play nice and need to be left alone. Trying to talk about what's wrong will only make things worse because not being able to is my problem.