selection bias is omnipresent which is why everyone is welcome to add facts to the discussion, as in the case in courts and the scientific method, so that scientists and juries can come to their own independent judgments rather than relying on an Ordained Authority. In science, if there is not consensus, we loop and add more facts until there is.
You're being intellectually dishonest if you think "Disclaimer: this comes from a conservative organization" to the HN audience doesn't have a clear well-poisoning effect. Maybe you should stop and consider who you're really trying to convince by arguing otherwise.