Good post - I enjoy reading everyone's thoughts on the situation. It's certainly been an adventure trying to follow this situation.
As for the above quote, I also gave it some thought, and my feeling is that it was Rivera who made those comments. Specifically, the comment that he was "less than thrilled" with the Nix hire. Just connecting the dots here, but Rivera was in SD when Nix and AJ had a falling out. I have no idea what really happened, but those left behind in SD seemed to have a bad taste regarding Buddy. Also, Rivera has ties to Fewell from coaching in Chicago, so he may have gotten some negative vibes from his contact Fewell, seeing as he was just fired by him.
Just pure guesswork, and it would be too bad if it was Rivera, because if we go the coordinator route I think he'd be the best candidate, although Russ wouldn't be too far behind.