If El Rushbo could bring Fred back from the dead, he would, but he can’t, so I expect both Limbaughs will be overt and closet Myth Romneybots shortly.
I think Rush doesn’t want to endorse in the primary and risk having his endorsement defeated . It wouldn’t look good for him .
His brother David can do it though , as he has far less street cred to lose . This is a quite telling development .