Apart from his obvious prejudice against gay people, it is unclear what “principle” Mr. Klein thinks he is supporting. It is the principle of the relevance of cake in a wedding reception? Wedding cake and baked goods at weddings started as superstitions from pagan Rome, and stacked pastry in medieval England. So, maybe it is “superstitious principle” that Mr. Klein is “defending”?
Given their online behavior after the story broke, an argument could be made that the guiding Culture War principle was simply to treat LGBTQ people badly.