iirc the article they says entered security 35 minutes before departure. iirc it doesnt say when they checked in or when they arrived at the airport.
so with a desk deadline of 40 minutes, the general principal should be that this should be sufficient time to pass through security.
We know what time they reached security and the 40 minutes is standard easyJet procedure and is more than enough time time get to security, you can there in less than five minutes easily.
So where (and why) did they get to, there is not much down on Level1 to occupy the time of people.
To me it points to those people arriving late at check in.