What's insidious is that these theories come up in the first place to shield bigots from reality more. Junk like the Soltreian Theory, Christian Identity or whatnot make it hard to disprove a bigot on the spot.
BIGOT: I hate niggers!
SANE GUY: We're all descended from Africans!
BIGOT: If 'Out of Africa' is true, it means whites are more evolved and therefore, better! OR That's a lie from the Jewish-Muslim-Zionist-Atheist-Feminist-Satanist-Reptilian Space Weirdo-Romulan-Xenomorph-Uruk Hai-Pastafarian-etc.-Conspiracy!
BIGOT: America belongs to Whites!
SANE GUY: But the Indigeous Peoples were here for 12,000-20,000 years while Whites are Europeans who were only here for a few hundred years and stole the former groups land!
BIGOT: *Soltrean Theory Wargarrbl*!
BIGOT: I'm Christian and I hate Jews and everybody who isn't a White Gentile.
SANE GUY: Uh, you're following a Mid-Eastern religious tradition and worship a Big Jew In The Sky!
BIGOT: *Christian Identity Wargarrbbl*!
Darn bigots and their darn "Goalpost Movement Theories"!