Both Rosanne and Samantha strayed into isms. Rosanne made a racist insult about a politician, Samantha made a sexist insult about a politician.
Socially, there is a lot more tolerance for sexism than there is for racism. A lot of media members have made sexist comments who are still on the air, but blatantly racist remarks tend to knock someone out quick. Remember Don Imus?
Even here on the boards, if you find someone making racist remarks they get banned fast, but sexist remarks will seldom even earn a warning. There's a member in politics who's referred to women he disagrees with politically as she-bitches, cunts, and shemales with such regularity that I exceed the forum character limit if I try to quote it all in one post, but a lot of people (even women's issues regulars) happily chats with him like there's nothing wrong with that shit (though potentially because he contains those sexist outbursts to politics forum).
Anyways, point is, both remarks are bad. Both warrant apologies. I made no suggestion about what the network should do in either case. It's largely going to boil down to the business impact. TV networks are corporations and corporations do whatever they think is best for their bottom line. It's all about the money (Rosanne may have been their #1 rated show, but they had to be worried about loss of advertising revenue, public boycotts, etc).