No you don't know what Trump thought...All you know is what he said...No one took Trump's statement seriously...He was speaking about his sister...We certainly wouldn't expect Trump or anyone to tell the world and his sister that she would make a lousy judge...
Trump has stated publicly numerous times since then that he would appoint judges in the vein of Clarence Thomas...But I'll bet that is one thing you DO know
I linked the video, I think Trump was very serious. In case you missed it, start watching at 15:45 and see for yourself his tone.