should still make it so you can only get PK'd if killed by someone who had PK permissions on you beforehand, or your death is resoundingly thematic, narratively appropriate, or canonical in feeling
slipping off map geometry or being killed as a matter of pretense (killed for the crime of wrong place wrong time for example) shouldn't go, because no development comes as a result of that
in RPG terms; PKs if you die as a direct result of your own stupidity, poor actions, and lack of foresight, and less because of circumstances where you were fucked from the getgo. if the metaphorical DM is watching, it's fair game
we're here for OOC enjoyment first and foremost, and we owe it to every player to make them not hate their character dying, even if we can't make them enjoy it
(though personally a really good death scene can be enjoyable even for the person playing the character)