it's not all that different. Saban knew he was leaving, lied about it, and stayed for the remainder of the season. Then he left abruptly.
Petrino knew he was leaving, lied about it, and then left immediately after lying.
Both coaches began to dismantle an already poor team and left it in worse shape. Saban had final say over his players in Miami, Petrino did not in Atlanta.
Petrino's is worse IMO,at least as far as the timing goes, Saban decision to leave, I believe, was more irresponsible as he was the GM, but the two are similar in my mind.
It's unfortunate that the system rewards coaches that are dishonest, or at least requires them to be dishonest in order to be rewarded, but it does.