We here are users helping other users
We have only knowledge based on our own experiences with Apple Genius Bar and repair services
We are asking probing questions so that we may understand YOUR experience as much as you do.
The forum is "finicky" - even for those of us that use it regularly. You had bad luck in that this happened to you on your own problem thread.
All the deductions you make sound reasonable. Unfortunate, but reasonable.
If I were you, I would call the Store which you visited - or go back in person (best) - and speak to the Store Manager for a precise explanation. It then would be Apple "policy" and not anecdotal.
You then could return here and enlighten all of us to the 'facts' of the matter so that next time the question is asked, we can refer them to your first hand knowledge in this thread.
Best luck.