Based on the article, it's because Google (and presumably other search engines) did not surface the website, only LLMs crawled it.
Even if some LLMs discarded it, only they were the ones returning the results to users. Occam's razor tells me that LLMs cited the website and humans were too lazy to check. That the stats ended up being cited is a lack of scrutiny on both the LLMs and the human that should have reviewed it.
If the end goal of LLMs are autonomous agents, i.e. removing human oversight, then this will be what proliferates on the web.
Even if some LLMs discarded it, only they were the ones returning the results to users. Occam's razor tells me that LLMs cited the website and humans were too lazy to check. That the stats ended up being cited is a lack of scrutiny on both the LLMs and the human that should have reviewed it.
If the end goal of LLMs are autonomous agents, i.e. removing human oversight, then this will be what proliferates on the web.