The most you can do is heal or isolate his victims. Which we can naturally handle, as we already have the doctor's corpse.
Or hope that he will target the mafia and fail his kills.
By the way, he doesn't have any protection against execution yet; it's just that executing him today and tomorrow is impossible.
Added 1 minute ago
Uran couldn't have fallen for it because Sesam doesn't play mafia often enough to be familiar with the concept of a feint and naturally execute it, as in this case. Many mistakenly think that creating an unpair requires an emotional argument. The fact that he creates an unpair almost guaranteed doesn't mean that other methods don't work.