Yeah, despite the huge unlikelihood of him getting a US visa

Stan is fighting the most oppressive and murderous regime in the world with his patriotism.
And the scene with the DOJ was absurd, His career would be dead.

One thing that was not well researched was the idea of a military age male flying into the USA on TWA with no visa. If he had visited a US consulate in a Warsaw pact country to get a visa he would have been watched by Eastern intelligence services, and it would be very hard to have gotten one in Yugoslavia or Western…

Monty, Yugoslavia was most certainly Eastern Bloc — for near 50 years. "Eastern bloc" does not mean Warsaw Pact.
Learning Russian was very common in Yugoslav schools.