If Rove is a professional politician, he is still one whether or not he has a client. It appears that you are entirely unaware of what it means to be a professional, as opposed to an employee.
I think you’re grasping at straws to keep from admitting a double standard was applied to Rove.
Simply because he has been involved in getting Republicans elected doesn’t require him to support all Republican nominees, particularly in his current situation. He should support all of them out of common sense, but not because there is some political code of ethics that says he has to.