Ideas should absolutely be judged on their merits; here we agree. Too bad that's not how humans work. Instead, they tend to choose whichever truth they like best based on how it makes them feel; politicians know this, which is why they don't bother crafting logically sound arguments backed with evidence. They play on peoples' emotions.
Moreover, the university is not a public square. You attend as a student, which means you are there to learn, not to share your thoughts like it's a real-life HN thread. Don't want to learn the material? That's completely fine. The solution is to not sign up for the class, not to whine about how "discourse is gone" just because the teacher doesn't want to waste time on every edgy kid's opinions. People didn't pay massive sums of money to hear you talk. They paid to learn from experts.
Ideas should be thrown into the public square, in the full light of day, and judged on their merits.