Sorry buddy but you’re full of shit, this is standard practice at tire shops. The reason you overpressure is that a tire at rest may not lose air noticeably, you overpressure to mimic driving down the highway when the tire is bulging out more due to centrifugal forces.
80 psi for a few minutes is not really that dangerous, the tires blow up at 120+ psi.
I won’t be as rude, but you are the one making a claim that exceeds both common sense and the warning on a typical car tire sidewall. A leak from a puncture area, bad bead seal, or tire failure point will show at normal inflation pressures with a water/soap test, as anyone in their backyard can attest to. You don’t need to simulate flexing and stress for this, in fact pushing the tire to its limits with high pressure will absolutely find a failure of the tire structure very quickly, which was the point of my warning. Maybe you’ve never seen or heard a tire explode. It doesn’t pop like a balloon.
I would question any shop doing this procedure from a manufacturer’s recommendations and from OSHA standards.