Gervais and Chappelle were saying different things.
Chappelle denies that transgender is a valid thing to be.
Gervais said he doesn't fucking care if you are trans or not.
One denied your existence, the other doesn't care. I think that's an important distinction.
(Of course, Gervais being a straight white middle aged man from a western country has the privilege of not having to care about others. Which is problematic, as well. But we know he knows that, too.)