Some of the other clowns in the circus might pull a stunt like that, but Trump is the Whiteface, the clown that emphasizes pride and arrogance.
He would never allow himself to do something that he thinks will look bad. Not to say his bungling incompetence doesn't do that for him, it's just that he won't do it as a conscious choice.
Clowns are somewhat interesting.the Whiteface is the know-it-all straight man, and the Auguste is the bumbling doofus who is the butt of every joke. The Auguste is the first to get a pie in the face. You laugh at the Auguste.
The Whiteface on the other hand is the person telling you who to laugh at. They tell the mean jokes to get the audience to laugh at others. This makes it so much more satisfying when the Auguste finally hits the Whiteface with the pie.
Anyway Trump couldn't tell a joke if his life depended on it, but he still fills the role of Whiteface in this circus. He'll pull stunts, but only if he thinks it will make someone else look bad.