If you had lived under Stalin for 15 years and directly experienced 4 million of your countrymen being starved to death under his dictats, the concept of "good" side and "bad" side is messy. Especially when you don't have full access to information - no internet, no newspapers, no radio.

The Finns fought on the "bad" side as well, due to the Soviet Union having tried to invade them already two years previously. Ukraine had likewise tried to get independence in 1917 which led to a 4 year civil war which they unfortunately lost.