These were not attorney-client privileged communications, as there was no attorney-client relationship between MN and CA at the time, and because the communications were not for the purpose of seeking or providing legal advice.
And if they WERE privileged communications, CA would have waived the privilege by sending them to JB (a third party). The privilege belongs to the client, not the attorney, so even if they were privileged communications, MN had nothing to say about whether they were released or not.
Only if he's alleging that JB violated an ethical rule. I'm not sure that's what he's saying. I think he's saying that JB's motion contained falsehoods, but where did those falsehoods come from? IMO, they came from Cindy, not from JB. Now, JB was unprofessional in not calling BC to confirm the story before putting it in his motion, but he probably didn't violate any actual ethical rule.