Rather's transgression was of a completely different character, and his transgression is what brought him down. FR was nothing but an agent to illuminate the transgression.
Hannity's comments reflect nothing more or less than picking friends and seeking commercial success. Certainly a big deal for those "friends" who feel slighted or slammed, but in the grand scheme of a million or so viewers, probably not a big deal. Heck, O'Reilly's ratings haven't tanked even in light of his disdain for the Swift Boat Veterans for Truth.
I guess he didn't learn any lessons from Rush. Rush thought he was part of the IN CROWD until he had problems. then they turned on him like jackals. But Rush's REAL friends stayed. Hannity apparently has to learn this lesson the hard way. But he doesn't have the residual good will Rush had.