Good news, it doesn't block! It just puts a red mark next to their name, so you can put less effort into that comment, if you choose. And, it's social. If some

Good news, it doesn't block! It just puts a red mark next to their name, so you can put less effort into that comment, if you choose. And, it's social. If someone you've marked green is also using this, and they marks someone green that you have marked red, then you'll see a contested red-green next to them, which is a good "you should probably reconsider" indicator.