I think he'd like to be the lovechild of Sid & Nancy. Saying 'but who cares' to C about whether Green Day are punk or not is sort of like kicking a bull in the bollocks. And it's not about the fanbase, it's about musical integrity.

It's an idiom. Means you might as well be caught doing something really bad rather than something just a bit bad if the overall outcome is going to be the same.