I just had a thought: when you walk through the downtown of most US cities, you see and hear a lot of "street preachers," and as far as I know even Christians find them pretty annoying (especially when they link their sermons to legalizing marijuana, as I have noticed is often the case). The other thing you tend to see is enterprising musicians with a hat in front of them.
Just about everyone loves the latter, most extremely dislike the former. Extrapolating to your situation on the bus -- what would you have done if some traveling musician had gotten up with a guitar and just started playing? Is it about the "being taught at" aspect, or the "disturbance" aspect? There are different levels of presumption involved.
EDIT: damn, I can't tab+enter to submit comments anymore on you guys' mirrored posts :p