yep. sums it up.
the board separates the batter and the glass, so the path of least resistance will probably give first (back housing).
The customer should have experienced issues long before the shattering point, and at least one would warrant a trip to the nearest AppleStore.
They would check for abuse, try to reproduce the error, and send you out the door with a new iPhone if everything went smoothly. But, I suspect some sort of physical damage / liquid damage that the customer did not want to shine light upon.
Glass in the eye? Apple would like to see your medical documents before they fall for that hogwash. Their case will get thrown out of court. You cant sue the makers of Brillo if a particle of their product gets embedded in your eye for some odd reason.
I really hope Apple goes through with putting innovated shock sensors in more products.
https://www.macrumors.com/2009/08/06/apple-researching-methods-to-detect-consumer-abuse-in-portable-devices/
More security for those of us who don"t treat their equipment like *expletive*, and a big *expletive* from Apple, to those that do