As for soul transfer, there is plenty of it going around.
Souls into objects: Skin-spy (functionally a bio machine), locks at the library (souls embedded into the mechanism), Wathi Doll
So, putting a soul into an empty vessel, that's a thing.
Putting a soul into an occupied body? ie something that already has a soul? I don't think there's precedence for that.
Soul transfer into another body is a curious thought. If you look at shae, IMO its likely each single body is more/less dead and soulless, making it open to transfer. This might explain why they are all amputed - a dead body that is only sustained part of the time would lose blood flow in its peripheries maybe...
If moe had a dead guy on standby to transfer to, and if in fact a single person could achieve such a transference, then maybe its possible.
I still think he's dead though. I can't think of, and haven't hear of, a situation that didn ruin the story for me if Moe lived, corporeally, through that encounter. If its explained later, then I'm sure it'll be fine, but I wouldn't count on it. There have been few, if any, answers or bits of information given to us in TAE that have explained things from PoN.