He was measuring his possibilities. His end-goal, as some anons have already said, was to get as much space as he could from NATO borders, wether it meant neutral countries or more countries in the socialist bloc.
In the case fo Germany and Austria, he knew as much as the Allies, that no party had enough power or occupation to demand an unifocation on their terms, like it happened i the west with France, Italy or the Netherlands; or in the East with everything east of Poland.
Point being, they had to reach an agreement. The soviet proposed basically the same plan for both Germany and Austria. Unification, of the occupied zones, neutrality of daid states, and free elections and all the cannonical liberties of bourgoise republics.
In the case of Austria the Allies agreed, and thats why Austria has never entered NATO, but in the case of Germany there was to much at stake. The Allies couldnt risk a socialist or even communist victory in all of Germany, so they decided to go their own way and form the German Federal Republic with the union of the territories the UK, USA and France had occupied. The reasoning was tjat they could always blame the Soviets for not wanting a unified Germany in their home countries, even with all the facts pointing otherwise.
And so, the Soviets had to form the DDR. The DDR was basically a product of the Allies not wanting to risk loosing Germany, wether it was to neutrality or to socialism.
In any case, the Socialist Bloc would win. If they got a unified, neutral Germany, it would mean way less border to defend, with all the implications it has. And in the case the allies say no -which is what happened- they gained a new state.