That many Russians died to secure Soviet control over Central/Eastern Europe is not proof that the Soviets were self-sacrificial liberators, but rather that in Soviet, and ultimately Russian, culture, human life is much more dispensable to those in power than it is in the West. The Tsars, and their Soviet successors, were tyrants who could decide the fate of any subject. To this day, the Russian leadership has no problem in carrying out assassinations of politically problematic people, even abroad. The Soviet-installed government in Poland following WWII operated according to similar principles and under Soviet directives, though not to the same extremes as the Soviet leadership. Pilecki is one of many who were brutally tortured and executed by the communists, many of them members of the Home Army. Both Nazis and Soviets took part in exterminating swathes of Polish society they saw as a threat or an inconvenience to their rule (e.g. Katyn massacre), during and also, in the case of the Soviets, following the War.
It is easy to lay blame at the feet of a handful of leaders and forget that in centuries the Russian people put their arms, their strength, their blood behind such. It is easy to focus on a single tiny person within the scope of history and say of course this person had no power and no complicity in evil and forget that the totality of the Russian people are complicit in the actions of their leaders.
Tell me, who was responsible for the hundreds of thousands killed in the battle of Verdun: individual soldiers? Scared to death, trembling, half-insane, playing dead under the dead, left without any reasonable choice, resembling more animals than humans? Or someone else, who actually sent them there?
The same was true of prior tyrants they embraced.