Craig Ferguson wants to stay where he is because no one bugs him and he can do what he wants.
Remember that this Leno mess started out as rumours because he was bashing the network a lot and NBC didn't like it.
Craig does nothing but bashing CBS and no one cares.
Because with Craig, CBS doesn't percieve him as a threat.
Leno has been on for 20 years hosting the oldest late night show of the bunch. He also has a bigger name recognition along with his "He has cars" shtick