...I don't know if you thought that by making a philosophical assertion, I was trying to defend OP. I wasn't.

That's a very good point, but it seems it depends on how "opinion" is defined. I think I was defining it too narrowly - the examples you gave are things I would call beliefs (in this case, erroneous ones). I was talking about subjective judgments such as "these people who do X are annoying". They cannot be "wrong" because they're talking about someone's subjective reaction.