That's what makes it perfect, his body is in a time out. The artifact is a sneaky workaround. The only way to stop his warmongering is to free his huge, powerful, nigh-indestructible body...which then needs to be stopped...maybe? At least he won't be able to do a Palpatine, playing both sides of the war, anymore...
Eh...your bbeg...just an idea my players are going to hate you for giving me... 😁