A surreal story! Kidnapping, ransom demands for milk and cookies, banks with "no service" during an emergency, then a last-minute change of heart from the kidnappers? Sounds like a bad movie plot. But hey, if it did happen, congrats on getting your brother back!
But there's a plot hole in your story. Bitcoin wouldn't have magically solved your "outrageous ransom" problem either. If you couldn't afford the fiat, what makes you think you'd suddenly have a pile of Bitcoin lying around that was enough? Centralized or not, if you don't have the funds, you don't have the funds.
I am surprised you are asking this question. This was a true life story that few members of my community knew about. These kidnappers were later caught by the police, and my brother identified them.
And when did this supposedly happen?