Seems like it's an act/character that got out of hand - probably due to too much drink. Doesn't sound like he was actually coming from a sexual place, and I'd guess the guy's feeling pretty stupid right now.
Obviously what counts is that young girl though. Such a horrible formative experience of live music.
I kinda like(d?) the band and think I'd be willing to move past it if he'd put out a statement (hiding behind that 'we' of the band seems weak), owned up, said he went too far, and demonstrably cleaned up his act.
He's a young guy getting attention for probably the first time in his life. He fucked up, clearly. The statement was his chance to say it was stupidity/inexperience, not malice. He fucked that up too.