99% sure that Chris Rock joke was written by somebody else. Award shows usually do that...aside from maybe a bit or two from the hosts. A presenter usually doesn't write them.
That being said, it seems Chris Rock didn't even know Jada Pinkett Smith had a medical condition. And who ****ing cares, I'm always in the opinion that a celebrity is not afforded the same decency that regular people get....assuming that celebrity keeps themselves in the spotlight.
For example, there is actors/actresses who keep to themselves and don't go onto TV shows and showcase their lives....then yeah, it's probably not a good thing to make fun of somebody like that.
But the Smith's, **** them. This is what you get.
But in reality, she has a medical condition but nobody gets up in arms when people make fun of bald guys, small dicks, being overwieght, being under weight.