Gladly.
1) It's a very risky maneuver to claim SK as scum, because if for some reason your lynchpool is full of scum, or for some reason your only target is scum, you'd be found out, and if you're still alive after several days you'll be found out too.
2) It's more likely for an SK to claim Vig than Scum to claim Vig, since then scum cannot explain the lack of a second kill, while an SK will be the source of a second kill.
3) SK is a Neutral/Third Party role... NOT scum, scum HAVE to get rid of him as much as we do since he cant joint, but he can help town until scum undoubtedly NKs him.
4) Leaving a leashed SK alive maximizes our chances at killing scum per day due to having 2 kills a day, while scum STILL can only kill once a day.
5) Eventually if he's not dead when reaching LyLo he has to be lynched before then.