[Nothing is written in reply. He hates himself for wavering on this when his head tells him that the answer should always clearly be what's best for Konoha. But he doesn't want to be dead, either, doesn't want to leave, and doesn't really want to make this choice. But duty comes first, and even if Kakashi can't do anything for Konoha anymore, because he's already dead, he knows Gai and Lee can, and that's important to him.]
Clearly they should just tie Bell to the bed to keep him from leaving the Sphere.