I read the article, and the comment you linked to, and some others near the start, but I couldn't handle any more. These people seem to think that this TA is some authority figure, magically trained in the art of paper-grading. It's probably just a student with no prior experience! Here's a hint to professors: if you don't want an untrained amateur reviewing the papers of your students, don't assign one to do so.

Also, I couldn't disagree more with the author of the article. Science is not a "fact," and the sooner that he stops thinking that evolution (or gravity, or even the roundness of the world) is something purely objective about which there can be no possible debate, the better. Historically speaking, scientists have always known various things to be fundamental, undeniable truths, and they have been corrected for nearly all of these things at one point or another. I wouldn't be too terribly surprised to see some ultra-complicated quantum physics paper which demonstrated that the world is actually somehow a mathematical flat plane.

Also, as I'm sure someone mentioned, he wants to correct content, and English labs presumably correct form.