The 'someone else' is air travellers. When a major terrorist plot succeeds using a car, cell phone, or computer, a different group will suffer.
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.
