Sean Payton opens up about why he left the Saints (merged)

Not sure. I think there is definite bias against franchises whose success disrupted the direction the NFL wanted to go. Payton's continued success beyond 2009 is not something the NFL was ready for, certainly not after they were forced to keep the Saints in New Orleans, post-Katrina. Remember, that was a Tagliabue call, not a Goodell call.
Doing what's best for business isn't the same thing as enjoying having to do it.