Apparently there is an effort to force Rush Limbaugh off the air into retirement. This has picked up speed since the incident involving Georgetown University law student Sandra Fluke. No radio show can last long without sponsors.
Radio stations can't just leave three hours of airtime vacant. Something has to fill that airtime slot. The mid-afternoon/early-drive slot is somewhat influential broadcast real estate.
Did nobody think that getting rid of Rush Limbaugh might result in getting somebody new who might be even more odious? Glenn Beck has a big enough stable of talent and just happens to share syndicator with Rush Limbaugh and Leo Laporte. Leo Laporte has a pretty big stable of talent too.
Keeping a neutralized enemy is sometimes safer than opening the way for a total unknown to have to contend with...