People in Congress already hate his guts, this will give them an objective reason to vote him down without drawing the wrath of trump. I mean he'll fume about it, but most normal congress people aren't going to stick their necks out for a proven pedophile.
Trump is nominating so many fucktards, you'd almost think the strategy is getting mired in conflicts about his staff picks for the first 2 years, get nothing done, and then associating the dissenting Republicans with Democrats (These RINOs joined the America-hating Democrat socialists...) to drum them out in primary so he can install some even further rightwing dipshits.