General question: This is a fine point, perhaps, but it's my impression that it was entirely possible that JG was indeed Caylee's father due to his close relationship w/Casey... right?
Also, it's not unusual, and doesn't reflect poorly on him, that one of JG's reactions to Casey's bombshell news -- delivered while he's in a seminar for a new job, after all her denials, fer cryin' out loud! -- might be adoption. It just means he wanted to consider all his options while still taking responsibility. He'd been treated badly by Casey already and had every reason to be wary.