He doesn't sound opinionated to me, he sounds like an insecure know-it-all.

Having an opinion is great. The very definition of an opinion precludes telling someone else they are wrong. Once there is a right and wrong, it's no longer an opinion, kwim?

I have a few family members in one group who are all know-it-alls. They literally look like they are competing to be the smartest person in the room at times. It would be funny if it wasn't so sad. I suspect that when it looks like that, it's probably one of those defense mechanisms that comes from a place of deep insecurity. When you look at it that way, it starts to feel kind of pitiful.

He's not particularly enhancing to your life, so I'd avoid him if at all possible, but if you are in his presence, why engage him on that level, especially since you know it's very unrewarding to engage with him that way? Let him spew his opinion, and don't worry about sharing yours. When I'm with those particular family members, I don't engage hot button topics, just engage when it does feel like it won't turn into a "let's put AP in her place."

He may not even care about where your opinions stand as much as he feels like arguing with and putting someone down.