You do realise of course you're suggesting an admin or mod would be the one being unfaithful in breaching either users' privacy whilst reviewing their PM's ??
I'm not sure what you mean, maybe the way I worded it was confusing; I'm saying that I encourage users to report unsolicited personal messages, but a global moderator or admin isn't going to post publicly about whether a personal message occurred i.e if you report a personal message in hopes to get it verified that it exists, that's not going to happen, since it technically isn't against the guidelines. Also, as Loyce pointed out; it might have been unsolicited for Lucius, but it wasn't for Amph since they were directed to contact Lucius. However, a global moderator or admin might consider it unsolicited enough to report, but it would probably require multiple messages for any action to be taken.
However, some users in the past have used DefaultTrust users to log in to their account, and verify the message exists, but I don't recommend that either. Since, there's privacy issues for other personal messages, and obviously a security risk. However, I don't think it's necessary either since Amph didn't deny they sent the message, but rather they were deceived.
If you mean by reporting it, it's putting both users privacy at risk; then yeah any personal message that is reported would be reviewed. However, it's recommended to use encrypted messages if you care about your privacy in personal messages, because they can be viewed by the admins, and globals if reported, which is technically something you risk every time you send a personal message.
It does seem as though a conversation occurred. As to whether of not there was a man-in-the-middle who was coaxing information out of either or both, we may never know. (then again both users could have been set up knowing they would bounce off of each-other. The scenarios are endless.
Right, which is what I'm most interested about, since it's a rather odd scenario, which we'll probably never get to the bottom of unless there's more instances where this occurs, and we can get a little more information. At the moment, it appears to be a isolated case.