Charles Koch is a libertarian, so he supports small government, an isolationist foreign policy, and open borders. It’s no surprise that he doesn’t like Trump.
Nothing exemplifies the degradation of FR more perfectly than the fact that it took until post #27 for someone to point out that the Kochs are libertarians, whose practical side makes them lean GOP. They are not remotely GOP-E.
The Kochs could buy and sell Trump many times over.