You got it - it's common sense. Why continue to focus resources on a task that has been addressed, that's only playing
their game, trying to get & keep him bogged down on a single issue they can concentrate opposition on. Trump has a very large to-do list, loaded with issues that are sacred cows to them. All he has to do is move on to another task on the "list", they have to shift their resources of opposition and a new battle starts. But he's energetic and fast moving, hard to pin him down and keep him that way. He's beating down their resistance by attrition. Wash, rinse, repeat....