Rights when missing a flight due to security issue

Earlier today, my wife was supposed to fly from Hamburg to Porto, with a stop in Madrid (purchased on the same booking from the airline, one way). She arrived at the airport in plenty of time (around two hours before boarding was scheduled), but there was a major disruption, which included the airport being closed and all departures stopped. Her flight departed later than planned, but as a result of the extremely long queues she had not yet passed security when the status changed from “boarding” and the flight disappeared from the departures screen. As she was near the front of the security line, she continued through and to her gate in the hopes of still making it. Once there, she found many other passengers in the same situation.

The flight was operated by Iberia, and an Iberia staff member led the large group of frustrated passengers to the Iberia desk, but after waiting for some time there was no sign of any further help or support being provided and she decided to travel home.

She received an email from Iberia informing her that she has been rebooked onto a flight via London - due to her nationality, she cannot transit (even airside) in the UK without a visa, so this rerouting is not a valid option for her. She has already called Iberia and they were unable to offer any suitable alternative routings before the 4th (she returns on the 5th, on a separate ticket).

She has already found alternative travel arrangements with a different airline. The ideal scenario would be for a refund of the Iberia ticket. Is that something she can demand? More generally, what rights does she have in this situation?