It doesn't matter what the reason is, Manchester still has very few slots if any available at peak times. That is why both easyJet and Ryanair have not based anymore aircraft there.
I have no fight in the MAN vs LHR debate, but that statement is completely wrong.
Easyjet based 2 more aircraft there this year, Ryanair 1 (plus a 2nd extra based in the August peak).
Easyjet are to base at least 1 more aircraft next summer, and Ryanir only have not based extra in line with their 'no extra based aircraft in the U.K.' mantra that has befallen all of their UK airports.
And that's not even touching the 2 extra based Jet2 this summer, 2 more next summer including 1 A330, 2 extra based Virgin Atlantic A330, 2 extra Thomas Cook A330, the 2 A320 Vueling base that has been officially applied for next summer and one extra Monarch confirmed.
But then, why let the inconvenient truth get in the way of your argument.