Things that need to be done to get an accurate reading:
• Engine needs to be warmed up to have proper ring sealing
• All 4 spark plugs need to be removed
• Install compression tester on one cylinder
• Hold down the gas and clutch so that the injectors do not fire
• Press the ignition button, wait about 15 crank cycles, then press it again to stop
Those are the proper step to get an accurate reading. If he failed to follow that, then just do it yourself. Super easy to do.