Why? Comments don't typically disclose "I am a corporate spambot" and yet such things exist, so you should probably read every comment as though it has some angle / vested interest. At least brians was nice enough to mention their bias in their profile. Most cases won't be so easy. Making people "opt in" to disclosing biases will just make it easier for the real bad actors to slip through.

brians seems like a good actor, which is why I assumed they might appreciate the feedback.

I agree there will always be bad actors on hn, which is too bad. I think the moderators try hard to combat it, which I am grateful for.