Then they came for the trade unionists, and I didn't speak up because I wasn't a trade unionist.
Then they came for the Jews, and I didn't speak up because I wasn't a Jew.
Then they came for me and by that time no one was left to speak up.
Martin Niemöller
I think it applies very well in this case.
The question at hand is, "What is acceptable in the name of defending ourselves against terrorism?" And "How effective do these measures have to be to be worth the tradeoff?" and "Who is accountable for measuring and deciding that?"
It makes sense to make a principled case even if the problem currently limited to air travellers. If "oversight is unnecessary, just do whatever you think will keep people safe" gets enshrined in popular opinion, it's going to be ugly when they get to the internet.
More effective than "security theater".
They first made us run our shoes through the X-Ray machine, and I complied because it wasn't that big a deal.
Then, they installed the full-body scanners, and I complied because I just wanted to get home for Christmas.
Then, they started requiring social security numbers when buying plane tickets.
Then, they began keeping all air travellers' fingerprints and retina scans on file...
The question is not against whom they're discriminating (clearly, that's not applicable in this case), it's to what length they (and, by extension, we) are willing to go.
This is about apathy towards injustices that don't directly impact you and a lack of foresight. I.e. Wow that's so wrong, I'd raise a stink if it happened to me.