Contrarian experts are really important imo, and I don't think their efforts should be devalued just because nuts might be attracted to them. As long as they're properly engaging in the scientific method I reckon that they're perfectly fine to quote.

So? You’re trying to engage in tu quoque without saying it explicitly. If you think the argument is wrong, make a counter-argument. Don’t just say that the arguer hangs out with people you don’t like.

Cliff in an expert, he worked in the Obama administration on climate, and unsurprisingly, he is being cited for having opinions the support the thesis of the article.