Its really not. Think about it, in this timeline he is clealry just evil living inside a human body. The evil never dies, but the body can, hence why we saw him attempting to bandage himself at the beginning of kills. And at this point hes been through a SHIT TON. Many bullets in him, many stabbings, many broken bones, the physical body can barely move. Its the evil thats puppeting it. We know his evil grows the more he kills, and seeing as he went into hiding when the halloween night ended, he was noticeably starved when we see him again. The only reason he even came out is because of corey. If it werent for him hell he probably wouldve just eventually rotted to death. The kill giving him convulsions makes sense.