Do we yet know why they sent the documents apparently without having made backup copies or why they needed to send the originals at all?
I'd have thought sending scanned copies by email, while keeping the originals safely under lock and key for subsequent forensic examination, would be the sensible course of action, as well as being quicker and safer then sending them by UPS or whoever.
To my mind, this is an example of Putinesque "implausible deniability," as it were, like Russia's response to the Salisbury poisonings -- the whole point is that it's not credible, but there's nothing anyone can do to challenge it, and it simply acts to encourage suspicion and cynicism about factual news reporting altogether.