I know the union did something about this the last time it happened. Can't remember the details, but it was huge at the time.
I hope it hasn't happened again...you can't stand someone down for NOT doing a job they're not trained for, or willing to do, particularly when safety is concerned.
It's all fair and well for the company to say "Oh, but you know what the CM has to do"...yeah, but the current CM's are both trained and PREPARED to take the lead in any emergency situation. Some people just don't want that responsibility because they're not comfortable with the role.