I don't see it as constructive criticism.
It's been explained that the gig was organised as part of the FaF events, and was deliberately designed to showcase the diversity that exists within folk/roots/trad music. To have done this with a mixed set of performers without drawing attention to the fact that some were lesbian, gay or whatever, would have diluted the concept to the point where it would have been just another gig.
As it was, it was an effective way of letting the outside world know that folk is an inclusive genre, and of showing a little pride. Or should that be Pride? ;-) I would have liked to have been there, even as a 'non-hetrosexual'