I voted to reopen this philosophical question (Opinion vs. Fact).
I do agree it could be off-topic for this site, despite the fact I have enjoyed the experience of thinking about it and providing an answer on it. I agree it is probably on-topic on the Philosophy SE (though I have not studied their charter).
What I disagree with is that it has been closed as a duplicate of an answered question. I don't think it is the same question at all though there is a superficial similarity. The original question was about the English sentence construction of "incorrect fact" and whether that is an oxymoron. I certainly agree with the accepted answer on that question.
This question is about whether it is philosophically acceptable to have an opinion on a demonstrable fact or whether such a circumstance has any meaning.
Merely stating that something that is a "fact" cannot by definition be incorrect says nothing about whether one can have an opinion on a fact.
Therefore I assert it has been incorrectly closed and should be reopened.
Whether it is off-topic or not should be decided by the community using the usual process.