8. They silently get up from the table.

Reason: It is improper to interrupt dinner.
An emergency (heart attack, choking, etc.) is an exception.
You’re hardly likely to hear the Royal Family say, “Excuse me, I need to use the restroom,” while dining together. When attending a royal dinner, it’s customary to discreetly leave the table if necessary.

They quietly rise from the table.
Although royals will inevitably need to use the restroom, they are required to leave as quietly as possible and return to their seats with the same level of discretion. This regulation is in place to prevent any disruption of the dinner’s formality and manners (well, at least they don’t explicitly forbid restroom trips).