There is a difference between one person being concerned about hidden opinions and the systemic effect of posters being able to unilaterally hide opinions from most of the readers. Defaults are powerful and there is a good chance that if the default is not showing, the most people won't ever see. That has a systemic effect on the nature of consensus, and not just an effect on individuals.

That being said, of course, these options are on a continuum. It is clearly better to have an easy place to click to see hidden comments than to have to go and dig through a chain explorer, try to find criticism in different posts altogether, or use some alternate interface. I'm still uncomfortable with the unilateral nature of it. A blog that participates in a shared reward pool is not the same as a personally-owned blog that is standalone, and I'm not sure that the same model of unilateral control by the blogger over conversations should carry over.

BTW since you brought up the issue of downvoting for reward and downvoting for visiblity being bundled, why are you proposing to bundle muting? I don't think it really makes a lot of sense. What I don't want to see is distinct from what I might want to hide from readers of my blog. Bundling them would seem to degrade the value of both. I might decline to mute someone I would prefer to mute because I have no intent to hide their comments from others, or I might decline to mute for hiding because I personally want to see it even if I think it detracts from my blog if displayed there. These are really quite distinct.