This is what always confuses me about these discussions: that isn't even "arguable." Kirk begins TUC with an explicitly racist attitude. Just because it's BASED on something that actually happened to him doesn't make it NOT a racist attitude.Whether these attitudes are racist is very arguable
The reason it is a racist attitude -- and not, say, an antimilitarist attitude, or an anti-imperial attitude, or an anti-war attitude, or an anti-immigration attitude, or even an anti-reconciliation attitude -- is because he extends his emotions to include the entire race and not just the particular people or even the faction with which he's had bad experiences.
This is important to note, because when Kirk does his heel turn at Rura Penthe he realizes that his judgement of ALL KLINGONS was flawed in the first place. Not, as one might otherwise expect, his judgement of Gorkon in particular or of SOME Klingons. As he even tells Spock later "Gorkon had to die before I found out how prejudiced I was."
No, he simply believes -- deep down -- that the galaxy would be better off if the Klingons just went extinct on their own. Given the opportunity to speed things up on that score, he would probably decline, which more than anything is why they didn't ask him to join the conspiracy.He's not genocidal, not even close.