I never questioned that he said it multiple times. In this one, he corrected the kid that he didn't say it should be overturned, he said it was a mistake. Kid says that's crazy. Charlie challenges him to try to figure it out. Kid is well spoken, well dressed, Charlie is pushing his mind to think.
I don't know if any of your Leftist sites mention it, but Kirk thought the CRA created a DEI monster that was anti-Constitutional in its suppression of free speech and in creating an anti-white bureaucracy.
Unless you think he meant that coloreds shouldn't go to the same school as whites, like Gutter seems to since he included it in his mindless cut and paste. In which case I'm done with the discussion.
ETA: My first paragraph is a great example of why the Left hated him. He treated that kid like an intelligent young man who could grow to have complex liberal philosophical discussions. The Left doesn't want that for black kids. The Left wants them to hear happy things as they grow into the next generation of subservient voting block.