„Kurica nie ptica, Polsza nie zagranica”.
You are misinterpretating this statement. Khruschev’s post-Stalinist propaganda in USSR was very pro-Polish. If Stalin considered Poland a sort of Soviet North Dakota, Khruschev considered it a sort of Canada. That was the idea. A lot of things Polish were admired post WWII contrary to every other period in history before when Poland was considered a backward province.
The meaning of the kurczak adage was that the travelling abroad from the Soviet Union was restricted to the Warsaw Pact, Cuba and Vietnam.
The point of adage was that the Poland was the foreign country most similar to Russia at every respect and it didn’t produce much cultural experience travelling to Poland comparing to any other foreign country.