...but I think the author is being honest about it being speculation. If you read the article to the end, his conclusion is that outlandish speculative claims

...but I think the author is being honest about it being speculation. If you read the article to the end, his conclusion is that outlandish speculative claims should be incentivized to be proven through a betting market that can reward proof proportionately. ie. Having the mainstream put their money where their mouth is. I don't see an issue with that. He isn't actually claiming that prior civilizations exist - simply that it's plausible that they did (depending upon what you interpret as "advanced").