As far as I know Stanisław Lem was not allowed to like anything from US. These days the soviet propaganda in Poland disallowed people to like anything that came from "the rotten west"
Such statement would hold somewhat true for the Soviet Union until the 80s, but not for Poland, whose society never stopped seeing itself as a part of wider European community, and because of significant migration in the XIX and XX century, also felt a connection with the US. Poland took advantage of Stalin's death to wrangle itself somewhat free of Soviet hegemony and starting with Gomułka's Thaw [1], adopted a more liberal model. It was still a dictatorship, but in comparison with the Soviet Union itself and also a few of the more repressive regimes in other satellite states, it was significantly more open. Edward Gierek's [2] rule only reinforced that course.
Don't get me wrong, it wasn't all roses. The inflow of Western culture faced many obstacles still, but those were often more of economical nature — in general books were translated, movies were shown in cinemas, the TV was filled with (somewhat dated) American and Western European TV shows, and Polish artists followed world trends in music (although with significant delay). The „rotten west” mindset never took root in Polish society and the authorities didn't enforce it with much zeal once the most repressive era ended in the mid-50s.