Calling it a democratic government is quite a short cut. They were in the middle of a revolution, in the process of deciding what the future of Germany would look like, no elections had taken place. In the population there was huge support for dismantling the Prussian military institutions, but the SPD decided to not only keep the military as is but also to use it against their political opposition. I’m not saying the Spartakusbund were the good guys, I’m saying that the excessive violence of the SPD was foreboding of what was to come.
The Freikorps consisted mostly of veterans of the Prussian army, and the specific division that executed Luxemburg and Liebknecht was led by Waldemar Pabst a high ranking official in the Prussian army.
What I am “implying” is that there was good reason why in the interwar period being anti fascist and anti SPD was not an uncommon opinion.