It's a complicated issue. I haven't followed the current situation you're talking about, but did see the previous iteration with the earnest account. And yes, I agree that it's horrible to see someone being harassed within a community you're apart of.
But - I don't think it does take a lot to get a negative rep score. If only a couple of accounts (with higher rep) continuously downvote/flag you can drop a user to below zero. My concern is that the second you start to take away someone's voice, you give up the right to your own.
But this is only for the 'bad' people. Perhaps theoretically, but in reality you can use the same method to silence almost anyone (maybe not stellabelle with her amazing reputation score). For example my account is nothing particularly special, but my rep is currently higher, so I vote you down, maybe get another account or two and do the same. Now what you say is hidden and you no longer have a voice on steemit. What i think you're proposing (and to some extent it already exists) is a toolset that will allow Trolls to not just harass, but silence others.
Perhaps allowing users to simply mute other users so they don't see the comments would achieve a similar result whilst minimising the downside? The comments of people with negative reps are already hidden/greyed-out. maybe allowing users to mute + shadowban particular users from commenting on their own posts only might also reign things in. For example, I could add users to a ban/mute list so that their comments didn't show up on my posts only?
I don't have an answer to this, but i like the discussion and hope others will chime in, maybe with examples that have worked in other online communities.
RE: Mechanism needed to combat trolls