SEO, like PR, becomes even more important when the product or service or ideology one is hawking is total rubbish. It’s not like climate change deniers have a dearth of time and resources due to having to do actual science, so it makes sense that this would be the outcome.
Also, “tricking” Google’s algorithm is relatively easy, albeit a time-consuming and soul-draining grind. As I’ve discovered from working with my long-term SEO subcontractor, some of the same dodgy tricks that worked ten years ago to boost a result in the rankings still work now because some loopholes inside that black box were apparently never closed.