I disagree with your definition of authoritarianism. 50.5% of a population voting to elect a representative or enact a referendum versus the 49.5% is authoritarianism. The same if the margin is 67-33, or 80-22 or 99.9 to 0.1. In any case, the minority is imposed upon by the majority. The individual is imposed upon by the collective, or even merely another individual.

Like Engels said, the revolution is certainly an authoritarian endeavor. The original expropriation was authoritarian, and the counter-expropriation would be a counter-posing authoritarianism. How can you take something from someone without imposition? If asking nicely worked, then we wouldn't be posting here.

The opposite of authoritarianism isn't democracy, but pure volunteerism. That would be nice.