You could make the case that around 1956, Poland was a bit more independent of the Soviets, but in 1948, the Soviets were firmly in control of Poland. The decision to murder Pilecki came straight from The Kremlin.
That is a narrow view on it. Pilecky was a British agent. Why should anyone allow Britain to exercise influence in Poland? It has betrayed Poland in 1939, it was not in a position and unwilling to seriously help Poland in 1944. And after 1945 Britain was irrelevant in Polish affairs both based on the above facts and according to Yalta agreements. It didn’t contribute in any meaningful way to the liberation of Poland.
And there were plenty of local Communists in Poland who viewed Pilecky as a traitor for the reasons above.
I fully understand why the man is viewed differently now and he deserves recognition but it was a different time.