WOW. Joking that someone from a certain race is more likely to steal your wallet is NOT a critical comment. That is stereotyping, which can be taken as a form of racism.
If you really think that people should have complete freedom of speech on TV, do you also think that people should swear their asses off on ABC at 4 PM? Obviously this is extreme but do you think they should show lynchings and Klansmen talking negatively about other races on primetime TV?
Using your logic, people should have the right to say what they want no matter how bad it is.
You say that its their opinion and no one has to agree with it, which is certainly true. But that doesn't mean that is the right forum for them to voice their opinions.
I understand its a joke and I myself have said some negative things toward other races in humorous contexts with my friends but you don't do it on National TV during a baseball game. Go to Comedy Central and bust out all the se hablaing jokes you want.
The reason FOX or any TV stations make decisions are not because they are PC or because they are the "Right" or "Wrong" thing to do. If the audience wants to see clansmen burning flags or racist jokes then you can bet your arse they would be on TV. Fortunately they are not because the "Audience" doesn't want to see them and therefore will not watch the Show and therefore will not watch the Advertisements that sponser the show.
Fox fired Lyons because advertisers may object to the comments and pull their ads and funding from fox.
All forms of non-cable tv exist because of advertisers. Lyons was fired to save advertisers the hassle of getting letters from consumers saying "Please pull your ads Steve Lyons is a racist"