With most politicians everything makes perfect sense if you assume they know it's real, but they have some narrow selfish reason to pretend otherwise e.g. connections to coal industry.
I'm not sure if it's scarier to believe that he's happy to spread propaganda from the fossil fuel industry, or that he's simply stupid enough to believe it.
(edit: and now I'm considering the terrifying prospect that he genuinely thinks Barack Obama faked his entire life story up to and past Harvard, and was some kind of muslim secret agent plant, which is much more terrifying than him just pandering to ignorant racists on the same topic for years)
Don't know if anyone outside of West Virginia really cares about keeping the coal industry going.
Also we may be able to use coal for other stuff - has anyone tried to make ground coal into soil with bacteria and worms - with growing soil erosion problem that could be a market too.