I find it difficult to believe that Poland would remain silent after its entire government was assassinated by its traditional enemy. No way. Nobody kicks the Poles around. It had to be an accident, else there would have been terrible repercussions.
Remember though that the Communist way is to spend a very long period infiltrating the society. They did it to the ex-USSR nations long before they took over, and they have done it to the US. There are probably lots of people in high and low places who can help smooth over this “terrible tragedy” with the right words, rumors, etc.