Redirecting a Mayor kill to a protected player. Is it fair?

Is it fair to redirect a Mayor kill to a protected player, or any player that wants to die, like a Ravenkeeper? I've never seen that happen, but i've basically only played with the same storyteller. Is it acceptable if the good team is losing badly, or is it basically a case of the ST deciding who wins?

This whole "ST deciding to kill a protected player/one that wants to die" isn't exactly a new concept. In an Ojo game where the demon guesses wrong, you have to kill a role that wants to die, or else they have no ability.