No, it's who he is. Trying to limit Sion undermines who he is. If Sion can only "die" once (Which is a ridiculous concept, since he can only die once period. This is NOT a video game) then why have Nihilus with his force eating ability, Ragnos with his sceptre and sword, Sadow with his force abilities, etc?
See where that leads? Into nowhere. No, Sion will be Sion. A is A. It's that's simple. Trying to weaken Sion doesn't help a debate, it makes it worse.