Of course you're absolutely right. What I'd really like to see out of Twitter is a fair, unbiased moderation team that's up to the challenge of operating at Twitter scale.
But I'm not even sure that's possible, and even if it is, it'll take a long time to build - and in the meantime, a system like the one I sketched in my prior comment, augmented with an ability to communicate "hey something looks to be going on here" to human moderators when necessary, seems like a reasonable stepping stone.