I'm also thinking about people that could get caught up at the border crossing back and forth on the regular because of this.

If you get captured as part of this Mobile Fortify stuff, it sounds like it's going to merge it with all other CBP records you have (including all border entry interactions). Pulling up at the passport desk or at a land crossing is just begging for the officer to see that an ICE HSI agent pulled you at a protest and scanned your face to pull you in for "secondary screening" for "higher risk factors" going forward and throwing nice glowing red targets on your back.