I must disagree on that. Fact is that the Baltic States initially became so called 'Soviet Socialist Republics' (SSR:s) when they where threatened into submission by the USSR. This meant a 'puppet' relationship where they had their own governments (obviously under full control of the USSR) and allowed the USSR free use of military bases. After a short period of time however these SSR:s 'voted' yes to be incorporated (annexed) into the USSR. There is absolutely nothing that points towards the conclusion that a 'puppeted' Finnish SSR wouldn´t suffer the same fate.
Indeed, there was absolutely no difference between the Soviet attutude towards Finland and the baltic states, other than the fact that they were proven to be wrong on Finland.