I’m not a customer of the airport, the airline chose the supplier and arranged the service. I didn’t pay the airport anything, I don’t have a point of contact for them.

Hence my shipping metaphor. When looking for support for something, the first rule of thumb is contact the person YOU paid, and don’t play middleman for B2B contracts that you have no say in.

You go to the airline, they compensate you. The airline files the compensation claim with the airport and passes on the cost to their supplier, exactly how it would work if you ordered something online and UPS lost it.

In your example, although I wouldn’t be caught dead in the US right now I would blame my airline if local airport security couldn’t get me through in time assuming I arrived with adequate time as advised by the airline.

Canada consumer protection seems to agree: https://www.cbc.ca/news/canada/march-break-travel-passenger-rights-9.7115327

The APPR sets out the expectations for airlines when situations happen that are outside of their control, such as extreme weather, emergencies, or security, labour and airport issues.

When uncontrollable events unfold, Canadian airlines are required to rebook passengers, free of charge, on a replacement flight — on the original airline or another that holds a commercial agreement with that original airline — within 48 hours of the departure time on the original ticket.