It is curious. So curious, in fact, that your whole conspiracy collapses in the face of it.
since their feuding with the SPD was instrumental in the rise of the Nazi Party
It takes two to fued. Maybe the SPD should've tried not shoveling millions of people into a pointless war, or not killing KPD leaders who opposed it, or throwing their weight behind the only candidate who actually was neither Hitler or aligned with Hitler, or not saying the communists were just as bad as the fascists (you know, like you're doing now).