You need to see it from Danielle's POV. (not saying she was in the right, but maybe understandable)
According to her, she didn't bring it up to "threaten", it was more bringing it up as Gregg was a hypocritical . In her mind, she knew what Gregg did to her roommate years ago. She said it took a long time to "forgive" him for that. She was probably thinking, we forgave you all those years ago (for something much worse) and you got the balls to drag my kid through the mud after it was all supposed to be done? @$%$ you Gregg!
Still shouldn't have called Earnie. Should have just waited til their next dinner party with Gregg and then let him have it.