I think it's more of a speciesism, specifically. And I don't think it manifested until Kruge killed his son. I think TUC shows him working through and overcoming those base instincts.I think TUC distorts Kirk's character to suit the current story. Kirk isn't racist, just look at "Balance of Terror" or STV: TFF where he drinks happily with Klingons. All the characters suffered badly in VI, IMO.