No, that's the exact opposite of my argument.
Opening is easier which is why pretty much every opener has a bloated average.
Batsmen who struggle at opening are in truth very poor players who would struggle even more in the middle order. I can't see someone like Shehzad average more than 27-28 at a strike rate of 65 if he bats in the middle order.
Of course there'll always be exceptions and outliers, but it holds true for the majority. In this day and age, if you can't succeed as an ODI opener, you are clearly not good enough in international cricket.
Most of the successful middle order batsmen in ODIs today would do even better if they open. The difficult of facing the new white ball and the supposed swing/seam is overstated.
Let's take India's example.. will Raina's average improve if he starts opening ?