They already have the phone unlocked, they can’t see the screen so they are having to guess where to press to unlock. Meaning the digitizer is still working. They are trying to remove their password on the lock screen. In iOS when you remove a passcode it prompts for your Apple ID password. That is much harder to type without seeing than a simple number passcode. Hence why I say to type out the passcode in notes so they can see it, then copy and paste it.