Quite so. There is also another, more unlikely option. Let's say that Finland falls as Stalin expected by the end of January and the Kuusinen government is installed in Helsinki. What if now, for one reason or another, Finland is not incorporated into the Soviet Union in the same way as the Baltics, but stays as a nominally independent Peoples' Republic allied with the USSR until Barbarossa? In this case Finland could be considered, at least on paper, an Ally on its own right.
I know the idea is a bit short on plausibility and would likely need a earlier PoD or a few of them. Why would Stalin want to keep up the charade of Finnish independence? Maybe he would hope a major part of the Finnish Left will see that the Red state of 1918 is being reanimated and thus approves the new government, weakening a possible guerrilla war and possibly even flocking to the ranks of the "Finnish Peoples' Army". Making the country easier to control would make it possible to reduce the amount of troops needed to occupy it, freeing them to be sent south. Stalin knows perfectly well Kuusinen et al. know they are on a short leash: giving his Finnish puppets some time to try to sort out the remaining bourgeois sentiment (with Red Army support, of course) would cost him nothing; delaying overt annexation would also lessen foreign outrage towards the takeover.