I honestly don't mind Jon having the stone back. But you need to see why he loses it: to prevent it being an easy fix and to allow us to explore and write the consiquences of a wish. Often this is excused by saying the stone has no power or is not available (it's pretty much the goku to use tropese ;) )
I guess we need to ask, what purpose does it serve for Jon to have the stone? What wishes could be made that won't over complicate the story? Why do you feel he needs to keep it?
I don't mind if you have somewhere you want to take it, it just seems odd to me. Even if Jon can't wish herself back to normal she might try to find someway to fix others or herself in some other clever worded wish...
Again I don't mind just wondering where the story would go after
