The thing about not voting for the partner rule... you heard what Bellamy had asked, right? That if someone kills their partner, we still can't vote for them.

[ she turns, so she's facing hiro instead of forward. ]

Sure, the chances of that actually happening are slim unless they have a good reason for it. But what if there are two separate murderers one week, and one just happens to kill the partner of the other person? So even if we manage to catch one of the killers, if it's the one with the already dead partner, we won't be able to choose them. So on top of that four, we'll end up killing another two because of the execution vote.

[ which is, really, one of the main reasons katara was so angry at austria. ]

I know that situation is totally hypothetical and might not happen, but if it does, we're stuck.