Simon Burns to step down as Minister for Transport; is this why?

So it is reported that Simon Burns, The Minister for Transport, is to step down from government, so that he can run in the election to become Deputy Speaker.

While the timing is of course dictated by the fact that a role has only just become available, I wonder if it is also connected with the fact that:

1. Simon Burns is MP for Chelmsford which has Stansted on his doorstep
2. Simon Burns is an avowed opponent ofa second runway at Stansted (and a third runway at Heathrow). Here's what he said in his constituency newsletter on those issues pre the 2010 election

3. The Davies Commission is due to report its initial conclusion in the next few months. It would be embarrassing if the Commission recommends pursuing either the Stansted or Heathrow options - and a Transport Minister comes out against.
4.  Essex County Council announced yesterday they would oppose plans to build a 4 runway superairport at Stansted - but that it had no objections to a second runway. Essex county Council is Conservative - putting the Transport Minister potentially at odds with his own local council.

I wonder if there is more to this than meets the eye...