Indeed, low temps will purple up some strains, but it should be noted that there is some controversy surrounding Ken. I personally couldn't care less about the drama that goes on behind the scenes between breeders, but supposedly Kens example of Bay 11 at (cringe) the Cup a few years ago, were the buds from an entirely different clone than what he was touting as Bay 11, which is (supposedly) GCXOG, although I believe there's some of Bodhi's App mixed in.
Are his genetic claims Bullshit? Maybe. Does it matter? Depends on what values you cherish. Purple is like Hansel. So hot right now. And it always will be. If the flavor is there, I hold fast to the persuasion of " Who cares!"