I must be missing the boat. All I heard from him, initially, was concern for Caylee, the girl he was tricked into believing was his granddaughter.
When he became aware of the "cover up," he refused to go along with it and support Casey. Next he learned that his son was being accused (and to whomever said Cindy can accuse all she wants, I hope it's not your name that gets inserted into a missing/presumed murdered investigation.
The fact that he acknowledges Casey's story is a lie doesn't make him full of hatred and as for a "grudge holder?" Yeah--if you kill a baby, especially one I knew and cared for and try to cover it up, I might hold a grudge.
I must be easy--I'll take the truth from wherever I can get it.