From what I can glean from the details, one has a young passenger ("socialite", no less), who upgraded during check-in from E+ to BF.
10 minutes prior to departure, they down-graded her. The alleged "empty" biz seats may still have been awaiting arriving pax, deadheading crew, or FAMs.
So they down-graded her. That's happened to me and many on this board (although in my case, it happened before boarding, but I have colleagues that had to relinquish seats in forward cabins). Yes, usually last upgraded is the first to be downgraded. I don't know of anyone that was forcibly "clawed" from their seat...people usually understand that they have to move back. No one likes this...
She should have had her upgrade fee returned, and possibly given a downgrade kit, and a voucher isn't bad, either.
Perhaps, given her background, there might have been a little bit of "DYKWIA" going on here? Really hard to tell from just this story.