It's not a standard if your tests are designed to match what your browser currently does.
The real tests of compatibility are those like Acid3 that are designed to fail all browsers equally. This one is clearly designed to fail all non-IE browsers.
I don't think they designed them to fail non-IE browsers, so much as they designed the tests for things they had already implemented in IE 9.
I think they could have avoided most of the criticisms in this thread if they had simply added a note saying something like "We made sure that IE 9 passed these tests before submitting to W3C, which is why IE 9 gets perfect marks below. Note also that these tests do not cover all of the HTML5 specification." (etc.)
Having IE9 at 100% on every test with no explanation really makes it look like they're trying to put one over on the reader.
The real tests of compatibility are those like Acid3 that are designed to fail all browsers equally. This one is clearly designed to fail all non-IE browsers.