I majored in Sociology, that sounds terrible.

I discussed the injustice of having general education requirements for technical degrees, and how these requirements do not correlate at all with the requirements of the workplace

That quote stuck out to me in particular. It's precisely the sort of question a sociologist might take interest in where policy is concerned. 'Are general requirements unrelated to a degree truly necessary in the pursuit of a focused career path? To what end are they included? Do they affect one's education for the better? For the worse? At all?'

General, rudimentary sorts of questions that haven't been refined there but interesting ones nonetheless. And if it was a 'one-off' sort of class unrelated to your degree, chances are that it was a low-level course. One would think that would warrant some leniency in expectations on the professor's part.

I'm trying to see where the professor was coming from but I'm not seeing it. You did include an opinion on the question here but if sharing 'your take on the subject' was required of you then there shouldn't be an issue there. That something like this was reported to the dean is rather peculiar.

If I were a Sociology major I would feel the same way about being required to take classes completely unrelated to my major.

I share this perspective to an extent. We had 'BA Breadth Requirements' at my university, where a certain number of credits from several areas were required in order to graduate. Things ranging from Fine Arts, Humanities, Languages, Transdisciplinary Studies, other fields in Social Science. More specifically, that rather large net included things like Drama, Music, History, Philosophy, various language courses, Business, Human Resources.

Some of those courses I could do without. They contributed little to nothing to my education in my opinion. It was just part of the grind getting the requirements over and done with, although even unrelated material was interesting here and there. That said, other areas were helpful regarding their overlap or their tendency to compliment one another. Sociology and Philosophy tend to go hand in hand, for instance, as do other social sciences like Economics, so those general requirements were welcome there.

Maybe I'm just being a prick? It's just something that's been really bothering me.

Don't think that's the case, not from what you've said at least. You were essentially given failing grades for completing the assignment. Unless details are left out, I can't see why the professor might have failed you apart from a difference in opinion.