You can promote valuable discourse without agreeing with one side or the other - or any. Sometimes, a good argument is more important than your opinion of the subject.
While that's theoretically possible, that's not my perception of how posts are shared here based on my very short time here. Mostly the things I see circledotted are witty responses or posts that are complimentary to the Hubski system or its users. For instance, a satire of the ban function with a discussion of the mute function from a positive perspective has 25 shares. A discussion of the mute function by someone who disagrees with the mute function has 2 shares. That's the discussion of the same topic, but one from a positive angle and another from the negative. Many of the same arguments were made in both posts. The post reflecting the best light on the site gets the most shares. It's just human nature to want to share things that people agree with and puts them in the best light.
I think the great difference is in the argumentation between the two posts. The way I see it, the critical post you're referring to has made no outstanding claims to be shared. On the other hand, the satiric one has been spot-on with enough people to be shared quite often. While discussion based on critique is important, it has to be thought-provoking in order to work, and this one didn't have that trait: it was just "I don't like it because reasons". Here's trivia for you: the same user went on to argue for banning "useless opinions" a bit later.
As much as I enjoy discussing this topic, I'm going to have to come back to it when I have more knowledge of how this site works. There's a difference between theory and practice in moderation tools, and I'm too new at this site to discuss it in any depth. I did see the post you linked and had replied in the comments that I didn't agree with this argument.