If you haven't read the forum for previous benchmarks, you would know that Micheal doesn't benchmark anything he can't automate because the entire website is run just by him. And it isn't that profitable. Spending the time necessary to run each test manually is time he can't afford to spend. If you want benchmarks run manually, there are some of linux running minecraft on the minecraft wiki.
Another fact is that people don't care too much about precise reproducibility. They care about some rough idea of how a game THEY ACTUALLY PLAY performs on hardware roughly comparable to what they have. Add a disclaimer to the benchmarks saying that they were not automated, though most probably wouldn't even care! But just benchmark games people care about!