I have never been asked for proof of travel while entering a CR.
As the for the MM comment...I am currently sitting in my hotel in Boca Raton waiting for my lost bags. The Baggage guy just told that since I'm a MM he is getting a floor manager to call me back to help expedite the process. I have said nothing about my status and have not been upset about the delay up to this point, he just took it upon himself to look into my file to see what he could do for me. I have never felt that Delta thought they had me trapped.