Powerjet1
So Ryanair had a problem with the tax policies of the Swedish government. That's when they decided to cut Luton to Vasteras.
Now there's nes government that Ryanair prefer. So they probably thought, let's reintroduce Luton to Vasteras. But then seeing that the aircraft schedules in Luton are completely full now, they thought about juggling around with the Stansted schedules and trying to fit in a Vasteras servive there. And yes, then was possible, so now we have a STN - VST route.
I don't think Ryanair had a big anti-Luton scheme to drop ("move") the route on purpose.