It literally says right on the facial recognition sign that you're free to opt out, just let the TSA employee know
Also, the spirit of the 4th Amendment is most certainly not "here, this is the easy way!" (yes, we are conducting mass surveillance but you can sort of opt out of one piece of it by going through a manual process over here that we will make you feel like you are burdening us by requesting)
I trust the TSA agents brain to not get hacked in the next 24 hours, a database run by them, not so much.