But, why would he be in his bathrobe? Yeah, it looks like a simple bathrobe. Very simple to take off. Like most bathrobes.
@E_Normus_Johnson, I don't know what time the concert was. Afternoon concerts have always existed. Even back in the 70s. I am guessing it probably was one, for a 14-year old to be there without adults. Did she say it was a nighttime concert?
I would think one's first reaction to the photo would be: Yes, it's disturbing because he's clearly undressed himself. Why did he do that?