If you can access using this so can others when you cross borders, are stopped by police, have spying spouse, etc. Those are real and sometimes fatal threat models.
You don't 'flash' a fake ios; you can use the bootrom exploit to put your modified version of ios into memory, and once you reboot you would get back straight stock ios. They could even make it reboot as soon as the password was harvested, leaving behind no trace. This is scary stuff. You can keep yourself safe by rebooting as soon as you get your phone back from border patrol, but many people would not know to do that.