Not as the Senate Majority Leader! He's the representative of the Republican party! If he came out saying Heil Hitler, we should raise taxes and confiscate all privately-owned firearms, I doubt you would be so forgiving. If he said, "I love Bill Clinton, and I think of myself more as a Democrat than a Republican" you would want him to step down.
I'm not questioning his Constitutional freedom of speech, I'm criticizing one of his remarks. As a representative of the Republican party, he's got to act with a certain amount of decorum, and if he can't handle that, he shoudl get the sack. And if he's going to go spouting off with ideas like that, which go counter to the Republican philosophy, he shouldn't be renewed as majority leader.