From Boing Boing: Damn right he should be arrested! Singing along to a tune only you can hear is really bad form. Lucky he wasn't shot on sight is all I can say.
Lucky for him he was in the UK and wasn't in America at the time. He'd be in Guantanamo Bay before he could say 'iPod'. Heh. Now all he has to worry about is being under 24 hour surveillance by the UK security services or being snatched off the street and thrown onto one of those whirlwind CIA world-tour package holidays.