Your point is well taken. It seems to me that, moral transgressions and Situationistes notwithstanding, the group decides what is welcome and what goes too far. The operating room staff would eject these guys, and rightly so. This particular subway car clearly voted in favour.

I think the iPod comparison in the YouTube comments is weak – the auditory and energetic experience of a live vocal performance is a Chateau Lafite-Rothschild compared to the Baby Duck of a cranked pair earbuds. There's also the minor quibble of how a squealing, pitching, flourescent white cold subway car constitutes a sanctuary :-)