My view is that if he's got a problem with women, we'll... he's got a problem.
It does hint at 'incel' in the way it's put, but the whole ad seems to be defining what he wants by knocking what he doesn't like. That attitude would make me move one PDQ anyway.
I can understand if some people feel uncomfortable in a mixed gender band - it can become like a family, and that is tricky for some people to handle. But in that case I'd expect them to express it better.
That said, if we can have bands like the phenomenal Girlschool, then we shouldn't get upset about all male bands (any Boyzone fans?) But personally, I can't see the fuss. I want to be in bands with decent people who are competent musicians and want to pay the sort of music I enjoy. I don't give a fig about their gender etc.
I have been in a band that had male/female vocalists and that gave us a very specific sound ( think Beautiful South) that would have been hard to achieve with MM of FF vocalists.