Well, if he did get something incriminating from his search for Caylee's body and held onto it, that would be the smartest thing he's done here.
I kind of wonder if maybe the A's convinced Dominic Casey that if he did find the body, he'd be some kind of hero. I'm sure if he had gotten to Caylee's body first, the A's would have been out in the media praising him for doing such good investigative work, or spun it some sort of way that if wasn't for DC, they would never have known what happened to Caylee. This would result in a lot of good media exposure for him and an increase in business.
I'm not saying that actually would have happened, but I can see the A's, especially Cindy if she knew she had influence over him, letting him be deluded into thinking he'd be a hero for finding Caylee's remains. I think he did the amateur thing of getting way too involved and getting way in over his head. And when all was said and done, he didn't find the body, wasn't the hero, and was probably chewed out and fired by the A's.
Hopefully he's learned from this experience, and decided it's better to come forward than to be the A's next scapegoat. Maybe he saw what happened to Kronk and got scared it might happened to him since he was in the vicinity of Caylee's body. Packing up and moving his business makes total sense if he's talked, and probably asked for time to make himself scarce before the defense and the A's have a chance to rip him apart in the media.
I think now it's all about clearing himself out of this mess before he's dragged into the middle of it. Maybe the SA needs time for LE to clear him so that when the defense and the A's attack, it'll matter as much as the attack on Kronk, which is mostly not at all.