Well this is probably the most surprising headline I've read on here for a while, what the hell!! Perhaps more than any other game this, for me at least, is a pretty visible slap across Microsoft's face. For me when Broforce was mentioned I automatically thought Xbox One.
I don't really have anything else to say about the parity clause, partly because it's all been said before and partly because a developer doing this says far more than I'd ever be able to say. Microsoft will never get more valuable feedback than developers upping tools and walking away and either they learn from it or they don't. It makes no difference to me as a gamer I have both consoles so I could play it on either but it does, or at least it should make a big difference to Microsoft.
I do wonder just how many other developers are thinking of doing the same thing and would jump at the chance if they got a call from Sony.