I have not PM'd them, as I don't know them. But, I hope some friend of theirs will let them know about this in the most respectful way possible.
I don't know enough about unregistered accounts on Ebay to say "yes" to such an idea. I'd be concerned for any possible harm that might come back to someone making a false bid, however justified. The hope, of course, is that an Ebay customer care rep's mailbox will be exploding with fraud complaints and they'll just take down the listing out of an abundance of caution sooner rather than later.