I know this is pretty old but I'm going to respond anyways and hopefully that's okay haha.
I am on the autism spectrum and though most men are diagnosed by age 8 (for women it's 20s and 30s!!) it's not unusual for people who are higher functioning to go undiagnosed or misdiagnosed their whole lives. I was only recently diagnosed and I'm in my 20s. He might not even be diagnosed, and also though the traits you describe are very common in people on the spectrum (to varying degrees of course, it is a spectrum after all and no two autistics present the same way), those traits in and of themselves can result from other conditions, personality, mental health, etc. Given that he's in advanced program and your description, he DOES sound like he has it.
I think it's really tricky because if he has an ASD, he likely doesn't even realize that he's annoying or stressing anyone out. Even if people are giving him subtle hints or passive aggressive hints, he's probably not aware of it besides maybe feeling some tension while being oblivious of the source.
I think you could talk to the adviser, depending on your relationship to him and ask him if there is a diagnosis or if he knows whats up, and relay your concerns. Or, in a way that wont cause him embarrassment or shame (not that anyone with autism should feel these but society makes us feel that way), you could quietly educate your coworkers about autism and let them know that you suspect he has it and encourage compassion towards him.
I also agree with asking him what he needs, or because he doesn't necessarily even realize hes behaving in a way that is seen as rude, kind of find a way to point it out without embarrassing him, or talk to him alone and just say "When you did __________ earlier today, I could see that so and so felt uncomfortable" or "I know you don't intend to offend anyone but when you _________________, it is seen as rude by some people, or seen as disrespecting boundaries. " Because it helps for us to be told things like that (in a kind, gentle and non-condescending manner, don't talk to us like were kids) so that we can try and learn what doesn't come innate in us the way it does with others. Part of it is also probably his social impairments, which affect every autistic differently but I know for me it makes me awkward and clumsy, "everyone in my group is sitting over there and I think theyre starting to work on our assignment and so does that mean Im suppose to go sit over there too?" kind of thing, and for other people it can present in ways that appear like the person is crossing boundaries without care.
The hyper focused on one idea or detail thing is pretty typical, but tbh it's probably part of what has gotten him this far in his education so far. I know it has for me. People with ASDs also have a tendency to fixate/perseverate and also tend to have difficulties switching tasks, so this could be part of the problem too with him hyper focusing on one idea.
I would say your coworkers need to try and be more patient and compassionate and understand that other peoples brains function and process differently, and so the best way to deal with someone who seems like they are autistic is not to necessarily try and change them (that would be changing who we are!) but to change the environment and make space for their mode of learning and functioning, while also finding ways to intervene with problematic behaviours (like lack of boundaries or understanding of personal space etc).
