The complaint is that jailbreaking is an "unauthorized" function that ruins demo units. But web browsing is a perfectly normal function that lends itself to much worse than what a simple "Cydia" icon can do to other customers testing the unit out.
Again - BOTH are inappropriate and neither should be done by anyone with a store unit.
Worse/Better is irrelevant. The device isn't yours - so you should treat it - and everyone else who might want to use it with respect.