Specifically denied is "paid performances, or any professional performance before a paying audience". If there was a cover charge to get in, it counts as work.
I think they vagueness of this points to part of the problem. There is no real specification of what makes an amateur performer in a musical event. I would assume since he was not contracted to receive a payment for his performance, it would be acceptable.
And just because there is a cover charge does not count as work. The cover charge is collected by the venue and does not mean he will get paid, which was specifically the case here.
And just because there is a cover charge does not count as work. The cover charge is collected by the venue and does not mean he will get paid, which was specifically the case here.