We seem to be back to square one, here, Dave.
I unchecked that box and I'm not seeing the pop-up (Little Snitch notwithstanding).
The only thing I can think of at this point is the next time you see the pop-up, log in with your Apple ID and then log out. (Apple doesn't make it easy to log out, so you'll have to search for the option; try the Apple menu...maybe the one to its right.) I'm suggesting that only because I remember having done it, not if it fits into a helpful time-frame.
