I think if they block this, and by doing so, he keeps the gov’t shut down, then they lose big. If he is unopposed, starts allocating funds for the wall, re-opens the gov’t, then everyone wins.
Do do you think that President Trump will declare an emergency, order the military to begin building the metal slat wall-like thing, and sign a continuing resolution that does not contain wall funding?
Or do you think he'll keep the government partial shut-down going until the court litigation has been completed? (Which would be several months, if not years.)