Just a minor point... the TPC doesn't run the tests. It defines the standards for the benchmark tests and certifies the results submitted to it. Vendors are usually the ones who run the tests. After certification, TPC releases the results. A full disclosure document is also available for each certified benchmark, but I don't know if they're available for public download.
Some TPC benchmarks are very expensive to run, upwards of $750,000 in some cases. Linux benchmarks will be run once someone decides to spend the time and money on them.
The tests are expensive to run, so who ever has deeper pockets gets to run tests, tweak their machines to run the tests better and then run them again.
If Microsoft really wanted to show that their technology was superior, they would pony up the cash to have someone test Linux. They haven't, and to me that suggests one of two possiblities.
Either they aren't serious and it's just a marketing scheme. Or, they are afraid to do it because they would look bad.
Either way, the benchmark is useless unless it makes a realistic comparison.