I think hushing is a good way to make someone go away in your comments. Some thoughts:

1. Is it possible to put this under ignore (or mute)? I don't use them so I don't know their full capabilities and functions but it seems logical that if I want someone out of my feed, I'd rather have their comments at the bottom as well. And it means that you don't have three ways of making a user go away. Either put it under one of the existing ones or make it automatic in some way. I don't think people want a third thing to keep track of.

2. It needs to be easy to un-hush someone. People change, both behaviour and opinions. Maybe you encounter an annoying newb and hush him. Haven't we all had an annoying newbie stage in our online ventures at one point? What if that newb becomes a great contributor later on? He's still hushed. Either have a way to easily see that a comment is being hushed, or add a link to unhush them to that comment next to the link and save buttons.

3. With three ways to negatively impact a user's visibility, I think it would be nice to have positive impacts. I was thinking about a 'relation number', a factor to indicate how much you vote on someone. That the more you vote on someone, the higher their comments and posts will appear. Not by a large amount, but enough to nudge it one or two places up. Badges have a greater impact. And to prevent echo-chambers, this number could degrade by a set percentage per week. This will also make sure that you only see a person higher if you still find their posts insightful.

4. What is the main goal of the improved comment sorting? It might be a good idea to get that clear. To prevent lowest-common-denominator, to make larger discussions still valuable, to give the user more customization? You mentioned them all in your previous post but I don't think they are all complementary. And the extent of this new sorting method is also unclear: do you want to simply nudge comments up or down a bit, or make comments rely heavily on the interaction between the user, or something in between?