Maybe, but apparently they took a financial hit anyway by canceling Imus.
The primary motivation here was ideological. Another motivation was to curry favor with the Rat machine in a more direct way, by removing an enemy of Hillary. Another was not wanting to be called names by professional character assassins. And yet another was to avoid a boycott.
If he had the same number of listeners and stations as he did 8 years ago, CBS and MSNBC would have found a way to keep him on the air.