my uneducated guess is he can only buy him self out if it's written in his contract that he can do so. He could try to resign but Watford are well within their rights to refuse that. Make no mistake about it Watford hold all the cards with this one.
I think it has to happen, like Siggurdson in the summer it's clear he wants to at least talk to us and once it gets to this point it's difficult for either us or Watford to turn back it's just about finding that magic number Watford will accept. Whatever happens now Watford come out of this looking far better than we do.