We had a GAF thread discussing his banning of cellphones with many members pissed off he would do this vs just allowing his material to be seen by everyone, but as you said, threads like this illustrate the very reason he needs to do this. Forget taking jokes out of context with cell phone footage or the joke still being in the "test phase", here we are discussing a news story where the only source is someone "claiming" to hear the joke and providing us with a TLDR version of it without any context at all or any way to substantiate the claims. Jokes, especially with comedians like Dave Chappelle, are all about his delivery and the stories he tells leading up to the jokes.
Example, there was a comedy special where he made jokes about Elizabeth Smart not being that smart. In the context of my post, this sounds terrible, but if you actually see the bit in proper context, it doesn't sound nearly as bad as my post would make it seem.