Definitely there are many college professors who will appreciate a well-thought out and coherent attack on their views. I have in my time profited by this. However, not all professors will (I have in my time lost because of this), and nobody appreciates a poorly-thought out and incoherent attack on their views. Given this payoff matrix you would have to be supremely confident in how well-thought out and coherent you were in order to make speaking up have better expected value than smiling and nodding.
you would have to be supremely confident in how well-thought out and coherent you were
This is pretty much the whole point, isn't it?
(And this is ignoring the other obvious factor, which is how much you care about what professors appreciate.)
Link.
Given the positive reactions, I think the professor seeded them with a positive impression of the site's content.