It's not optional, whether you believe it helps or not. Incivility on HN will almost certainly result in your comments being taken less seriously (especially as they plummet down the page and are ultimately flagged), and will eventually just result in your account being banned.
That's happening consistently to the alt-righters I do see on HN. Why own-goal yourself by calling them names? Call out their arguments, flag their comments, but remain civil.
Regarding moderate Republicans: I think we're talking past each other, and that we agree. It's the specific language of the pledge that I think is tricky for them, not the substance of it.