"as they searched for an undocumented immigrant who had received a deportation order to leave the United States."
"The search was conducted at the request of Immigration and Customs Enforcement"
Seems completely reasonable.
Did they tell CBP that the person was on the flight? Did they tell CBP that the person may have been on the flight? Didn't they know for sure?
Don't we have computers now?
What happens if I don't have my citizenship papers with me? Is ICE going to take my word that I'm not the person they're looking for and I'm actually a citizen?
Why should I, a natural-born US citizen, be obligated to carry my citizenship papers around with me in any of those situations just in case ICE decides to show up? I have certain rights as a US citizen, and one of those is that I expect to be able to travel domestically without carrying my papers and without ICE detaining me.