Anti-Communism was intense and powerful as soon the October Revolution occurred. The USSR was invaded by seventeen nations including the US shortly afterwards and further suffered a trade blockade.

If the US was being nice to Stalin during WWII, it was because they needed Russia to defeat Hitler (Oh, and previously, they'd been nice to Hitler hoping he'd take out Stalin but ole Adolf had an inconvenient "I am a tricky military genius" complex and things didn't work out right).

Also, anti-communist campaigns somewhat abated in run-up to WWII because Stalin managed to turn the world's communist parties into extensions of Russian policy so they could be used to quash radical movements (in the US, the CP was far preferred over the anarchist IWW etc, In Vietnam CP supported the French going into WWII, etc).

And maybe a random US official was fooled by Stalinist theater but I'm pretty sure the situation of the US government was looking the other way in the same that any state looks the other way when a friendly state does something embarrassing.

The USSR was invaded by seventeen nations including the US shortly afterwards and further suffered a trade blockade.

Which had precisely nothing to do with the mass repressions in the years following.