DSA is basically a parking space for one of their aircraft for the night. There is no offices for easyJet, no crew room, no crew, no admin etc. based at DSA.
Obviously if you class that as a 'base,' then that's fine, but you are wrong.
I think this will be argued to days if it isn't cut short.
The top and bottom of it is that every night an easyJet plane lands in DSA and the crew stay in a hotel. The plane then departs in the morning to AMS etc. and swaps with an LPL/MAN based machine and then that new aircraft flies the remainder of the days schedule and then lands at DSA in the evening, the crew again staying in a hotel. Its an on going circle.
LPL or MAN, for example, work completely differently. Crew arrive at the airport, visit the crew room, grab their plane, do a days work and return to their homes. The plane will then continue to fly for the remainder of the day and it starts again the following.
Do you consider FRA, CMB or SIN to be EK bases? What about SIN for QF? For goodness sakes, EI have more flights out of LHR early morning that U2 does with DSA all day! And they night-stop at LHR also! But again, they aren't 'bases.'