Genuine question. What about the professor's statements were inaccurate or incompetent? Is the sample size really too small? Is the claimed conclusion about free will invalid? Or is the criticism just the dismissive tone toward the student?
The incompetence originates from the disregard of the parent commenter's question/concern. It's the result of not engaging in good faith with your student, not necessarily the conclusions drawn. As I mentioned in my original comment, the value in taking a philosophy class (especially as a student in a different field) is the chance to engage with both the professor and your peers; it serves as a veritable petri dish for developing one's ability to succinctly articulate and debate topics. If you're expected to sit in a philosophy class and just absorb the material without any contrary thought, something is seriously awry. It goes against the very nature of why humans pursued philosophy in the first place.
Furthermore, it seems strange for a professor of philosophy to so easily dismiss criticism out of hand. Of all subjects, a philosophy professor has a pedagogical imperative to entertain contradictory positions and explain why or why not one ought to follow a line of reasoning. In addition, the question about the merit of a small sample size could itself serve as a valuable aside in teaching fundamental notions in the philosophy of science.
Note: This is from the perspective of Western analytic philosophy, but the spirit of debate and discussion is no less integral to the continental tradition.
I mean N = 12 is incredibly small to make such a sweeping statement about all of humanity but further it implicitly accepts that 1. free will is demonstrable via the experiment, 2. the reaction wasn’t preempted by free thought leading to the decision, and otherwise, 3. you’re a bad philosophy teacher if you’re trying to prove philosophy with statistics, imo.