Well yeah, because if you lived in Sapphire or Opal and someone tried to come into the bathroom while you were waiting, you could just clear out without anyone even thinking you were up to something! No harm, no foul! Sure, you wouldn't have been able to kill her, but you wouldn't be caught doing anything weird either!

Whereas if you left a bathroom that didn't belong to you after someone was already murdered and someone saw you doing it, that would pretty much put you right on the executed list!