I think comparing adding a climate denier to the editorial board of NYT to the Holocaust is a slippery slope fallacy.
The Holocaust is an historical event whose content and truths have been clearly documented in the 70 years since they happened; it was a human horror directly inflicted on other humans through a clear and direct and obviously immoral path.
Of course climate change is likely to result in far more deaths. Those who deny it are either ignorant, dogmatic in an extreme, or have ulterior motives, as any rational person can observe, using well-established scientific principles that there will be an outcome that is easily predictable, catastrophic, and will result in unknown horrors.
So if we agree that that outcomes are similarly horrifying, why don’t I agree with your premise? Because I think, and argue (perhaps ineffectively) that one of the learnings from reporting on the election is that without understanding how all viewpoints are being presented and understood, without a truly balanced reporting and opinion, we will once again be lulled into a set of what appear to be obvious truths. We keep fighting a losing battle, or perhaps are winning the battles too slowly. Without recognizing why, how, and what those who have alternate views believe, we’re doomed to convince ourselves with increasing fervor and certitude that any other argument should be dismissed prima facie.
Said more simply, the reason to listen to other arguments, is to understand what approaches will effectively help those who believe them see and embrace an alternate viewpoint. The alternative is just to keep yelling, and this does not seem to do much other than create highly sub-optimal conditions for effective change.
Read the other NYT op-ed writers having strongly liberal bents. I mostly cheer and feel better because I agree. But I don’t necessarily feel that they are helping me know how best to understand how we actually solve the problems.
I hope that answers your question.