What everyone forgets about the USSR's space program was that it consisted of a lot more than a man and some dogs and a cavalcade of hilarious disasters. It was a vast, incredibly-successful program that set all of the records for being in space. For several years, the Soviets owned space and, vitally, possessed the ability to track and receive radio signals from any spacecraft they wished. If we'd only pretended to land on the moon, they would have come at us with receipts.
"As you can see from dis image, they jus vent to Bermuda for a veek."
If you think they'd have covered for us like a bunch of bros, well, we'd already been through this dance by the time of the moon landings. In 1960, an American spy plane was shot down inside Soviet airspace. Khrushchev waited until the Eisenhower government had spun a few lies about it being a weather research plane before revealing to the world the truth: It was a spy plane, and here's the pilot to prove it, and oh look, here's the big fuck-off camera he was carrying with him. If they had the opportunity to damage our political and scientific standing on the world stage by revealing we'd faked the moon landing, they wouldn't have hesitated for a second. And why would they? They were still mad about the voices in Rocky And Bullwinkle. That kind of insult takes decades to heal.