Private Messages are named that because they are supposed to be Private! That means between the two individuals concerned and no one else, unless permission is granted to publish it.
I am not the moderator involved in this discussion but would have deleted any published PM were it in a forum I moderate. I know how it feels to have a PM sent to someone else published, as it has happened to me.
You can block PM's from any member except for Moderators. They can send a PM to anybody at any time regardless of whether that person has PM's blocked or not.
Barney