As of today, September 9, 2021,
If you use the search "polygraph" with the search engine Yandex.com in the Chrome browser, there is a hit for Antipolygraph.org on the second page, which would be the 17th result.
If you use the search "polygraph" with the search engine Yandex.com in the Tor browser, there is a link on the first page at the very bottom for Antipolygraph.org, about the 10th result.
If you use the search "polygraph" with the search engine Yandex.com in the
Epic browser(which has built-in VPNs), there is a link on the first page for Antipolygraph.org, about the 7th result.
Searching "polygraph" in Google with the Chrome browser yields no results on the first five pages, so I stopped looking after that.
It is not uncommon for Google to block controversial topics either by choice or secret government order. If you Google sites like purenudism.com, enaturelive.com, or bebaretoo.com, you will not get any results that show those actual websites. However, Yandex search engine will show them. Those websites are hosted in the U.S. and feature family nudity which is perfectly legal in the U.S. All of those sites are run by the same people and they have had their fair share of legal battles to which they prevailed. Since those sites feature child nudity, U.S. search engines like Google just gave up and blocked them. Yandex is a Russian search engine and Russia somewhat legalizes child nudity, or they just don't care, and will show those sites and similar sites. Same thing with this antipolygraph website. The U.S. government deemed this site too controversial so since they have no legal course to take it down, they just had the U.S. search engines block it. Other non-U.S. search engines will still show this site with a "polygraph" keyword search.