Because "cancel culture" only exists insofar as the general public stops consuming the content in question.

Some random actor says the N-word in a hateful way: "oh no we need to address this quickly before consumers stop watching our show or network as a whole because we support actors like this." - cancelled

Randy Marsh says the N-word: "oh hey look at that, this is one of the most watched episodes of all time and we have no financial reason to address this in any way." - not cancelled.