I mean, of course. The alternative was that Germany takes all of Poland and gets to be more agressive against the allies. The Soviets taking half of Poland was a massive benefit for the allies.
Half of europe being behind iron curtain is beneficial to allies too. Now West got plenty of cheap workforce... Today's China is great too in a sense :)
Looking at Poland army in exile, I bet if those people shot in Katyn were able to escape, that'd have helped allies more than decomposing bodies helped the local ecosystem.