That will force another Constitutional Crisis because the Senate is allowed to make its own rules, not the President. The President's "opinion" of Congress' status is irrelevant.
That is why McConnell, with Boehner at his side to show Republican unity, must state that they will not accept the appointments as a proper legal act and will treat the positions as still vacant, and that these people have no legal authority.
-PJ
A fight in court is inevitable.