Hmm...it won't be as strong then. You have to apply an assumption like:
1) Scum *will* make sure a non-scum dies if they can
2) They can make sure a non-scum dies
3) Ignore alien as the rest of the scum won't help them
4) There must be a scum that was in danger of dying yesterday
In any case, something then applies. But it's not immediately clear to me what it is. Also isn't clear that any of those assumptions applies.
In any case, not particularly useful outside a gedankenexperiment