Two wrongs don't make a right. When your position becomes "I have a right to mock you," you've lost the argument in my eyes. You've confessed that argument is insufficient and you need to rely on insult to articulate yourself in this instance. Maybe you're right, maybe you could have articulated a point that would sway me if you had given it some more thought, but that's not evident in what's in front of me.

That comment isn't my favorite, but it isn't an attack. It's still an assertion of the commenters position, with language that's stronger than I'd prescribe but within bounds in my estimation. Flag and/or downvote it if you disagree.

If you want to know what I personally believe, on a postage stamp, I wouldn't say people "have no right" to make such assertions (I don't think it's a productive or interesting line of conversation), but I think it's a bad call to make them (I think it's reductive and misses the forest), so I'm sympathetic to that perspective.