And also, if that protective beam formed around him in cold water, maybe that would happen, you have a point, but he went back into the Avatar State there in the Avatar Returns, and in the Avatar State, if they wanted too, Im sure they could unfreeze Aang with firebending, which might mean they did want him found around then. And, the ring went around to freeze Appa, which means Appa should be in that time too.