Easyjet for a few years have been getting a bit of a reputation of shying away from fight. More than once, Ryanair have put their tanks on Easyjet's lawn and within 12 months, Easyjet then decide to significantly reduce flying to the relevant airport
If Easyjet are perceived by other airlines as always relcutant for a fight, then the obvious strategy for Ryanair would be to open routes like Luton-Amsterdam or Luton-Geneva, sell tickets below cost and wait for Easyjet to pull out. As a major player in the European airline market, Easyjet have to find a way to signal in a way that their rivals believe will be backed up by action, that they will not easily surrender their core markets to ensure they are not always targetted by rivals.
Luton is one of Easyjet's major bases - Easyjet need to signal to Wizz that they will defend their position at Luton robustly so as to stop Wizz from trying to open LTN-AMS or LTN-GVA next year