Because the Russians are also liars of course. Or they claim those results aren't meant to be about people, ignoring that Zond 4-8 were unmanned test versions of a Soyuz equivalent to the Apollo 8 CSM, and also ignoring that the reason claimed for the hoax was to one up the Soviets.
Why would the Russians lie to protect a secret meant to fool them, or at least make them look bad.