Personally, I find someone who carefully considers how their words will impact others and demonstrates empathy and understanding more authentic. Their authenticity is in that they genuinely care for others and the world around them.
I agree but, for me, PC speech doesn't demonstrate those things. It demonstrates a parrot. That's about it. They care less about the people around them and more about signaling that they care.
I think if we're talking about people in public positions then NONE of it is authentic in the first place, whether it's genuinely PC or not. But if we're talking about some guy at a party who is super PC, I'd just be thinking he's a big phony.