zeuhl you could say that about anyone, the guard was an old chap and the stress the lad was causing could have given him a heart attack, who's to know.
If I were sat on that train I'd be pretty annoyed at the lad, I'd have probably got up myself and had a word, and I'm 5'8 and 12 stone, if he were bigger than me I wouldn't have because I would have thought I couldn't make a difference.
I wouldn't call it mob rule, I'd call it an obnoxious little div annoying someone who dealt with it.