I don’t care if Dave believes it or not, he’s attacking people from a position of power who are at danger in our society. It’s not an unbreakable rule, but it’s the core context used when trying to decide whether it’s productive. You can say a lot of terrible things about people who are hurting and elicit a chuckle from at least some subset of the population, that doesn’t make it good (in the good for society sense) comedy.
That’s why there’s a world of difference between KG and Chapelle, and no lack of consistency in people that think KG made a harmless joke and Chapelle is contributing to a trans panic that both oppresses and endangers lives. And it’s not a mistake. There have been other comics that have had off-color sets that when confronted about them thought about it and realized it could be harmful and wasn’t really that important to keep. It’s not his job to make trans jokes and that’s a very different comedy than simply being “incendiary”.