These are misrepresentations of his sometimes not very responsible rhetoric. Just for folks who are even trying to be remotely fair, lots of libertarians think the Civil Rights Act is/was problematic, not because of its effects, but because of its regulation of private, not state, discrimination and its expansion of government power over property rights and freedom of association.
Kirk’s version of the dumb “replacement theory” had nothing to with antisemitism, and instead was about immigration and the belief that the left was trying to replace native-born Americans with immigrants. He would notice all the left wing anti-white rhetoric and instead of dispensing with race, would take it up by arguing high immigration was at least partly about trying to dilute the white vote.
These also look like AI summaries, which are totally shockingly not very accurate.