I find it astonishing that any checker would, knowingly, degrade the systems on the aircraft, without telling the people actually flying the aeroplane. If it had been my check flight, I would have been hard-pushed not to punch the guy in the face. I'm still in charge of the aircraft, when I get checked, in my airline, and I would strongly object to this kind of meddling.
Regardless of the skills, or lack thereof of the pilots being checked, no one deserves that to happen to them on a route check. IMHO, the guy who did it is a moron.
Beware the Law of Unintended Consequences; you only have to look at the consequences on this thread. Not exactly good publicity, is it? Never mind the fact that said moron, would never be able to predict the end-result of his little "trick".