I love Joey Pants, and really hope Nolan and him work together. But, I do wonder if the reason he didn't get the Gordan role is because he played Ben Urich in the Daredevil movie, and those characters are very similar. Like, when Frank Miller wrote those characters, they become alternate versions of the same.
I don't think there are elaborate reasons for not casting him in a specific role he himself dreams of... Nolan simply had Gary Oldman in mind for it.
I don’t know if this has been posted here before (or in any other thread) but I thought it was a very interesting read and it has made me more appreciative of his films. I already was but things like these, rich in content (at least in my eyes), give you more of that.