I suspect that the passenger quoted is wrong, in that it's really the airport operator whose contingency planning should deal with "what to do with passengers who are evacuated from a plane" rather than (jointly) with the airline, but:
"I asked if tea and coffee could be arranged and this fell on deaf ears. We had to be escorted if we wanted to go to the toilet. It felt like the staff were more interested in security than our wellbeing," he said.
But, after all, Build Another Aisle is a retail property business, rather than a transport company, so why should it bother having "provide free tea and and coffee" in any of its contingency planning? More evidence, if any were needed, that it's a self-serving monopoly that needs to be broken up, and competition restored.