Advertisers really only care about one thing - the bottom line. Does advertising on a particular show help them sell more widgets or not? Anything else is irrelevant to them as it should be. If a show does something to provoke the viewers to boycott the advertisers' products, most advertisers will likely pull their ads from the show. It's really as simple as that.

To those who would force an advertiser to continue supporting a show they find disagreeable, how about this analogy: Would you have forced the blacks in Montgomery, AL to continue riding the bus system in the 1950s when they were forced to sit in the back of the buses or to give up their seats for white people? When Rosa Parks ignited the rightful protests against those discriminatory practices, blacks across the city boycotted the bus system. They worked with their churches to set up car pools and other means of transportation. The bus system tried to sue to force an end to the boycott but they lost in court. In the end, the boycott was effective and the bus system had to end its discrimination.

Forcing an advertiser to support a program it no longer deems in their best interest or that they find offensive is, to me at least, little different than those who tried to end the boycott against discriminatory practices. Bill Maher is free to say whatever he wishes. That doesn't mean anyone is required to listen to him nor does it mean that advertisers are required to pay him. Freedom of speech doesn't mean that you're guaranteed an audience or a paycheck. If it were otherwise, you might as well force people to go to restaurants that have lousy service and bad food.