Well, pissing off the pope is not a simple thing, nor easy to do, especially for personal gain and publicity. Trump apparently would like a war on catholics, just to stay in the headlines. Baiting catholics is really old-school Klan activity, done as a diversion from the ennui of lynching blacks every saturday night. It should solidify his aryan brotherhood endorsements and consolidate them.
When the pope criticized his plan, he would have been better served to ignore him, but that is not in the Rump's DNA. He will play it until the airtime it gets starts to wane, then he will go back to giving cruz and bush ulcers.