I can only guess that this is a way to motivate lots of Easyjet staff to find an alternate job ASAP - it's in effect saying to people that they can remain nominally employed so there is no gap on their CV, but they should spend the next 3 months focussed solely on looking for a new job. Alternatively if people really really need cash now then take your chances with redundancy money.
That said, the people at the top should be taking a deeper paycut than just 20% - they will certainly be working very hard in the next few months to save the company, but it fails to recognise that somebody on 500k per year can afford a reduced income much more easily than someone on 20k per year. Very poor leadership