He was not sharing a joke with her, he was sharing it with his audience, and it was funny. satire and irony and biting scarcastic humor works, when your audience knows it.
When an isolated is not isolated by a known track record of being funny and reads about "retards making fun od retards" and is delivered deadpan, it is not readily interpreted as being funny, it read as a deliberate spiteful remark, delivered properly it could have been funny, ad i would have laughed
only side I am coming from is that there is a difference between deliberate hate speech (which is how your post read), and making a big fuss over a joke.
"my mom was governor of alaska" - couched in a comedy show renown for satirical humor, and it was funny.
"Nice...a retard who is only hired BECAUSE she is a retard being used to make fun of a politicians retarded kid.." - delivered deadpan by an unknown person in a random internet debate site is not so obviously funny, it reads as deliberately hateful. (especially when you then go on and continue hateful posts about peoples fat asses ect, your tone is 100% hateful, how can we automatically know the difference?)
I am not spun up at all, I am just pointing out that your post came across as being offensive, and illustrating the difference between what the show did and your statement, and there is a HUGE difference, so sorry if you fail to see it.