Just something to put it in perspective, 9E has about 4,000 total employees and there are what? About half a million DL retirees? How often are 9E employees really bumping them on flights? Proportionally it's probably not happening excess, here and there but you're retired take the next flight and chances are there won't be any 9E people listed.
But 9E being wholly owned, everything they do is for and contributes to DL and all your profit sharing. It's very clearly different from the other contract regionals and Virgin. Also as a pilot I know it can be hard for us to remember there are things that go on in a company that don't involve flying and there are other employees who are equally as important that aren't pilots. Many many 9E corporate employees work side by side every day with DL employees doing work directly for Delta and with Delta.