@Checkboard
Surely the authority to "remove" Command (albeit temporarily until retraining has been carried out) is covered by the Part D Training Manual of the Company Ops Manual required for AOC?
As a Trainer (Line, TRI or TRE) you have been trained and tested by the Company Training Standards dept and are therefore deemed responsible/knowledgeable/trusted enough to make the decision to fail someone on a check.
It is not a pleasant thing to have to do..... but sometimes it is required. In my experience I've never had anyone challenge my decision. Yet!
As to the original post, I don't know what the Trainer is trying to prove. As a Checker your role should be passive - ask the occasional question or ask if the candidates want to discuss anything in particular but interfering for no operational/safety reason is a no no. Failing someone on the outbound of a check would be a very difficult situation to deal with -but you just have to advise the candidate of a factual, identifiable and unambiguous reason for the failure and its consequences ....... then you have them on the jumpseat watching you like a hawk!!
A4