It seems evident to me that the DL board is thinking very clearly on this one. They are resisting pressure from the institutional investors to do the deal without the pilots on board for a very good reason. They simply need to look out of the corner of their eye to the HP-US mess as the US East pilots file silently around airports in mass protest of the Western proposals.
There certainly seems to be some very rough air ahead for US and the lesson apparently has not been lost on the DL board.