The thing is, it should be about electrical safety for continue use, not personal preferences about installing the latest gear.Although it is down to the person doing the test at the time, and being rental, he may aim to get things changed to be safe as possible.
I'm with you there. The main thing this one swings on is whether that RCD works.The faulty RCDs would of course bring a C2. Potentially dangerous. If there is a serious fault, the rcd may not trip, resulting in injury.
I'm thinking it likely that he started with sockets, then found the RCD issue. I'd have personally tested the rest anyway, as there are parts readily available for that board.