I think he was objecting to your presentation of your opinion as axiomatic fact. (Notice, for what it's worth, that I said "I think" and not "Actually, he was"

I think he was objecting to your presentation of your opinion as axiomatic fact. (Notice, for what it's worth, that I said "I think" and not "Actually, he was". The core meaning is the same, but the former phrasing makes it more clear that I am aware the statement was my opinion. Acknowledging that something you say is an opinion is an important part of having a healthy discussion, I think.)