To make a blanket claim on the basis that somebody 'might' sing a copyrighted song is offensive to the extreme and should be resisted. If it is general practice, it is yet another nail in the coffin of folk clubs.
Similar moves were afoot some time ago here in Ireland with the Irish Performing Rights Organisation IMRO.
They decided to move in on venues were traditional music was played; at first their moves were strongly resisted by Comhaltas Ceoltóirí Eireann, but when IMRO offered to cut them in on the deal it became a case of 'about turn - quick march'.
Don't know how things stand at present, but wheels tend to grind slowly here.
Jim Carroll