A swelling battery would not show glass breakage as external pressure on the glass. It would show the opposite. So unless Apple didn't check closely enough to determine the direction of the breakage, this wouldn't apply.
I wouldn't trust the customer; I only need to look at how people treat their property after purchasing it - little wonder things go wrong, devices fail and batteries explode. Treat your stuff with respect and you'll get many years of reliable service out of - treat it like a football by constantly dropping it, throwing it around and being rough with it - expecting something to go wrong.