Makes sense. But note that the opportunities provided to a top pick are also because the scouting department rated him highly in the first place. If they pegged Cousins as a low(er) round pick compared to RGIII, it was based on their own evaluation of the talent. That evaluation won't suddenly go away unless the two players project vastly differently in training camp, games etc. This was the case with CyrusK and SeantrealH – it was evident that CyrusK is going to need a lot more time and effort so irrespective of their draft position, Seantreal is starting (albeit at different position than CyrusK was drafted for). I am glad the Bills did not fall into this trap and forced CyrusK into the lineup. Their thinking probably is that an experienced underperformer like ChrisW is better than him at this point.
That being said, RGIII may be done as a Washington starter if Cousins stays healthy and performs anywhere close to the likes of Russell Wilson or Kaepernick.