Your comment implied that this was following the traditional pattern where moving away cancels an action before it takes place. I hope we at minimum agree that the Lock Screen uses a unique behavior that doesn’t exist anywhere else in the UI. I really think you’re just confusing this third interaction mode we’re describing with the traditional mouseup mode that has existed for 3 decades everywhere else.

The simplest comparison point is the calculator app which behaves exactly as you described: if you put your finger down on the number 9, a 9 won’t show up until you lift up your finger. OTOH, if it worked like the Lock Screen, a 9 would show up, but would then be removed if you moved your finger away and lifted up. But again, nowhere else works this way.

If you think this is good interaction design, do you thus think the calculator app has bad interaction design? That it should instead be adding numbers immediately and then retroactively removing them?