Except you’re forgetting one thing. If the deathnote cannot kill in circumstances that are possible for the victim to die, it will default to a heart attack. Saitama cannot be killed by a heart attack and no sittuation fabricated could possible kill him so nothing will happen.
I am Silver Tongue, I am an artist. I have many characters and you can check out my art in the art tag. I occasionally practice witchcraft though I don't do anything too complicated. I am girl 2 and don't know what else to put here.