He got ripped off but maybe not intentionally. It's useless doing compression tests on engines this small because of the dead volume inside the compression tester which is huge compared to the volume of the combustion chamber. High exhaust timing will also drastically reduce the compression figure shown too. An ABx engine that's still got a pinch will hold compression almost forever whether hot or cold. I tried it with a well run in (~30 hours running) plane engine and simply gave up after 45 minutes.

The only thing that's important is how quickly the compression leaks away but even this is hard to judge. Basically if you can turn an engine up against compression and still feel resistance for a few seconds then it's fine. Even at idle a car engine is only up against compression for about .01 seconds.