You know, it completely hadn't occurred to me to report him in any way until I read all these comments. I am slightly horrified by the extent to which nastiness from students is clearly normalised in my day-to-day existence. I have, in fact, emailed a sort of general theoretical query to the harassment people, it'll be interesting to see what they come up with. I don't think I'd want to file a formal report, and even if I did, I was freaked enough at the time that I didn't get the student's name. And your point re escalating to actual assault is very well taken. The body language was not pleasant.