That's an interesting take on the situation. From what I'd read, Stalin wanted Eastern Europe as a buffer region between him and the West. Stalin didn't want any more surprise attacks into Soviet territory like what had happened in 1941. If that were the case, Stalin would have grabbed the region regardless.
I believe the agreement to give him Eastern Europe was made at Yalta; late in the war he couldn’t have done anything without the approval of the US & UK. They were feeding his people, and his army was on its last legs. It was one thing to chase a starving, beaten army back to Berlin; quite another to fight 2 countries that in comparison to the USSR and Germany has suffered rather light casualties (the Axis armies that were lost in Stalingrad alone were almost on par with US casualties for the whole war).