Totally agreed. BUT, at the same time, I'm not at all surprised that they DIDN'T test this. It's a lot of manual work to build those dummy libraries, or to clone employees' existing libraries, and then to cull through to find issues. It's even possible that they did some limited testing of this but didn't either dig deep enough or use the libraries long enough (days, weeks) to see the resulting issues. I highly doubt it occurred to them to look at those dummy libraries AFTER the test, when disconnected from AM - it's just not a logical test to run from a coder's perspective - so they wouldn't have caught the music removal bug even if they did test the libraries. NOT making excuses - they should have tested them - but nobody does proper testing internally anymore. Nobody. They depend on beta testers to sort their bugs, and clearly this was not properly beta tested.
But regardless of what testing they did or didn't do, the same bugs exist in Match. So they've absolutely no excuse at all not to fix them. It's impossible for them to deny they knew about them.