I think he WILL do it. The rats are not even negotiating. If there’s no reason to think they will come back to the table, nothing is gained by extending the misery any longer than he needs to, in order to show their intransigence. As the poster above said, declare the emergency, order the construction to go ahead, and then he can sign a continuing resolution.
Good news is, one of us will likely be right!
Better he leaves it on his desk...with the comment that it won't get signed if the 9th Circus weighs in....give them a week or so to stew.