The student does discuss the professor’s stated criteria, but she doesn’t do so to distract from her paper’s shortcomings. Instead, she discusses the professor’s criteria in order to apply it to her own paper, which she mistakenly concludes wasn’t graded according to the criteria.

The student doesn’t draw an evaluative (or prescriptive) conclusion. Instead, she draws a factual (or descriptive) conclusion from factual claims; those claims just don’t support her conclusion very well.

The student confuses necessary and sufficient conditions. She treats “reliable evidence” as sufficient for her paper getting an A, but in her premises, “reliable evidence” is necessary. The fact that her paper was supported by reliable evidence isn’t enough to guarantee her an A.

The student is making an argument about her own grade, but this isn’t why her reasoning is flawed. Instead, it’s flawed because she confuses a necessary condition for a paper getting an A with a sufficient condition.

The argument only addresses one kind of grading criteria— the professor’s criteria that only papers with reliable evidence will get an A. The student never confuses this with “objective criteria.” She just argues that her paper wasn’t graded according to the professor’s criteria.