I think the difference is that Leinart, with as much exposure and notoriety as he still has, is held to a higher set of circumstances than the fans, and his life was somewhat professionally (and personally) affected by Whiz, even though I think Leinart should take responsibility for his own demise in AZ. Therefore, he comes off as having sour grapes and completely lacks objectivity. IMO, it was an opportunity for Matt to take a free shot at Whiz.
He could've gone the professional route and just said, "no comment," or tried to give a true analysis as opposed to mitigation.