Oh Bullshit.
Geez. You just HAVE to manufacture drama. Lebeau had the decency and the class to see that Butler had served his time and that it was the right thing to give him his shot at the DC position. For God's sake, he'd been waiting for it for like 6 or 7 years. If Lebeau had taken a DC job somewhere else your theory might hold water but he didn't.
Imagine for JUST a moment that Lebeau walked in to the office and said, "you know fellas, it's time for Kevin to take over the reins. I'm ready to move on."
I personally think it was more of Art2/Tomlin decision as not wanting to lose Butler. I think LeBeau turned down the "consultant" role because he knows having the old boss hovering around, whom many players have unwaivering loyalty to, wouldnt be a productive enviroment for any of them.