Plane Silly:
Stansted doesn't allocate slots. EZY would have historic or Grandfather rights to the slots that it holds. They can't be redistributed in the way you suggest.
I'm not suggesting they just take them away from EZY, what i'm suggesting is that in the future, when other slots become available, that they have a preferred operator in LS. With this, MAG would give LS first dibs at these other slots.
Merely a suggestion if they want to work more with LS than EZY