The demon is not gone . This is not a spoiler but your misunderstanding. 2 orochimaru justu being is referring to his arms beings sealed. As most ninjustu require hand signs to be activated. These are not spoilers but miss understanding.
Lol! I feel like there's a lot of misunderstanding about the demons/spirits and sealing. Don't forget Shukaku prevented Gaara from sleeping. He had terrible insomnia in addition to all the other problems.
