Someone not being a BLM supporter, doesn't equate to them holding the opinion that anyone should be oppressed. Only someone who views everything through a binary lens / is trapped in dualistic thinking, would suggest such a thing. One shouldn't automatically claim someone else is an asshole for not agreeing to think the exact same way they do.

It didn't say BLM supporter. It says black lives matter. If you take offence to that, that's a you problem