While privacy is a legitimate concern, I’m not sure whether this argument is fully consistent with the team’s position that “if you can’t trust your moderators they shouldn’t be moderators”. Yes, mod access to PMs has been restricted, but doesn’t that mean isn’t that a sufficient privacy guard?
I am with @tobiaseigen that the ability to move posts from PM to topic was not a bug but a feature. Their previous practice of even asking for explicit permission makes it particularly difficult to use the privacy protection argument but even in procedurally less refined cases, I don’t really see a problem.
For example, I have more than once had people reply-by-email to a PM in a manner that made it apparent that they believed the reply would go to a public topic (the opposite also happens, of course). I have also asked people via PM if they could contribute something to a specific public topic and they were happy to do so, but - you guessed it - wrote their reply as a reply to the PM.
I also welcome new users via PM with two questions that sometimes lead to nice self-intros that would be a valuable contribution to the “Say Hi” category and so I ask if I can publish them.