Eh, pure random is probably better anyway. In any combination of pairings of {2, 2, 1}, unless scum is the {1}, they are given the opportunity to WIFOM us by:
choosing to kill their own investigating cop, while framing the other subset (providing us an 80% chance at a 50% incorrect scum result, 50% IC town result, or a 20% chance of a 100% IC result)
choosing to kill their own investigating cop, while framing the lone player (providing us an 80% chance at a 100% IC result, or a 20% chance at a 100% incorrect scum result)
choosing to kill the secondary cop and framing within their own subset (providing us an 80% chance at a 50% incorrect scum result, 50% accurate scum result, or a 20% chance at a 100% IC result)
If the scum is the {1}, they can kill either cop and frame within the opposite subset (providing us with an 80% chance at a 50% incorrect scum result, 50% IC town result, or a 20% chance of a 100% correct scum result)
The thing is, while generally speaking lynching any returned scum result is the correct play based on them having a strict 50/50 to be scum - it's actually not that difficult for scum to manipulate the majority of scum results to be returned on a framed player rather than themselves. And that in and of itself creates a loophole for scum to allow himself to be copped - and thus WIFOM.
Having no system to LL & Datswan's investigations gives scum no power to manipulate the results. A scum result would represent a true 50/50 - and while they may collide their investigations, they're more likely than not going to be fine.