I don't really have a problem with the concept, so long that the TSA's assertion is validated that 1. they are not building a nationwide biometric facial ID database and 2. that images are generally deleted immediately after use (compare ID + live photo, give result to TSO, when TSO hits next for the next person data is gone). For #1, the TSA seems to have taken pains (judging by prior documentation on CAT, not sure about CAT2) to make sure it does work offline, including a minimum amount for the solution to work solely on battery power and to have standard proprietary batteries.
(Also for anyone with objection to being in a facial ID database - I have bad news if you have a US passport or US visa, you already are. Some states even send all drivers license images to the FBI biometric database. I will play devil's advocate and say that the statistic is 37% of Americans have a valid/unexpired passport, it's more like 57% for valid passport ever, but still probably under 50% for images useful for facial recognition based on how old they are.)
I do hear the concerns in that it may be potentially discriminatory and that things often start with an opt out, then become mandatory.
Personally, having my fingerprints read for multiple purposes (including GE/NEXUS), my photo in the federal government's possession from my passport and GE/NEXUS - I don't see an automated local solution like this adding to any privacy issues beyond what I have already provided. So I don't object to it.