A) Guy with Kings definitely has every right to be pissed/withhold tips indefinitely. Calling the floor seems appropriate. If after the dealers comment someone with a diamond exposes their hand, I'd still expect them to get the pot.
B) At the local cardrooms I play at here in WA, it is unlikely that this would get the dealer pulled. But that's strictly low stakes. Higher stakes at top caliber room in Vegas, I would expect she'd get the hook.
Of course, at the higher stakes, it is a lot less likely players would need to be asked if they had a flush.
