He enrages liberals and flushes out many non-liberals (of various sorts ) who will gladly jump on board with liberals in their contempt of other conservatives who offend liberals.
For what it's worth. I don't defend Robertson per se. What he said was heavy handed, and the type of thing best reserved for Bill Maher, Comedy Central, some talk radio and other venues of ill repute. Nonetheless, the idea that liberals are shocked that someone would point out, however sloppily, the facts about what liberalism so sloppily promotes (moral relativism) is laughable. This is a movement that has no problem unzipping and pissing on anything and anyone that gets in the way.
It's basically Rush Limbaugh being offended that some radio host might be biased. It's a football fan complaining that rugby is too violent. It's a die hard Trekkie accusing a Harry Potter fan of being a geek. In short, the left has absolutely no place to yell offense at what Robertson said. I hear worse said about opponents of abortion or gay marriage by respected news anchors. It goes down from there.
Sure, what Robertson said was not altogether accurate. It deserves better than he gave. But then, the moral relativism that was shoveled into the mainstream over the decades often lacked substance as well. Many argue for that relativism in ways that make Robertson seem like a Rhodes Scholar by comparison. And in the most basic level, Robertson is right. He just didn't say it well.
But I will not join the post-modern conservatives whose favorite sport is shoving daggers into the backs of fellow opponents of the Leftist juggernaut. Smart conservatives would use this and build on it to point out where he was right, and defend him against attacks from outlets and individuals who have no problem saying far worse about people who disagree with them. It remains to be seen what post-modern conservatives will do.