“Many would have been considered traitors in their own countries.”
Considered traitors? They WERE traitors.
Not necessarily - many foreign soldiers volunteered to fight the communists - this would not make them traitors, since they had no allegiance to the USSR. A similar example would be foreigners who joined the U.S. Army during Vietnam to fight the communists there.
“They WERE traitors.”
What if you were a Ukrainian father of German heritage who saw his parents and siblings perish in the 1932 Holdomor - along with 10 million others (while the world covered it up).
When the Nazis rose to power primarily because of its anticommunism and it drove out the communists, who would you have fought for?
http://www.lib.ndsu.nodak.edu/grhc/order/general/sinner.html