It has nothing to do with blurring Delta/Delta Connection. On the right (FO's) side of the 900, the emergency door gets in the way. Check any of Comair's 900's. It says Connection on the left, not the right.

http://jetphotos.net/viewphoto.php?id=6094527 (Left Side: Connection)

http://jetphotos.net/viewphoto.php?id=6052090 (Right Side: No Connection)

The only thing they are doing to blur the distinction is making the airline logo much much smaller on the nose.