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.
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.