The idea of (2) might not make sense, but here's the thought: scum!Joseph's true role does something, who knows what, probably some things similar to what he said. Maybe it effects killing without actually killing. His team attacks someone, and the next day he claims to have targetted that person, so they die tonight. Then the other team attacks that target during the night, killing them, "confirming" Joseph's claim.
There are some issues, like this claim gets more and more suspicious the longer the night deaths makes sense under a hypothetical like this. With the system described above working for scum, we'll get one kill every other night guaranteed, but then they could both happen upon the same target (like with XP), or Joseph's team could hit someone previously attacked by the other team. So it's a little hard to account for extra deaths, unless there are too many.