Let's ask a couple of simple questions.
1. Was it the aim of the Nazis to gain control over territories which they saw as being rightfully Germany? Answer: Yes.
2. Did the Communist government of the Soviet Union provide material support to the Germans' gaining control over such territory, both through agreeing to German territorial revisions in Poland as well as by providing them with resources that assisted them in subsequent conquests elsewhere answer: Yes.
The logical conclusion is that Stalin did support one of the prime aims of Nazism, assisting Germany in gaining control over territories they saw as being rightfully German. That is a simple historical fact, the truth of which is not dependent on the motivation of the Soviet Government for providing that support.
Gosh, this is fun.