I responded to your statement that 'The _ONLY_ moderating action internet citizens have is moderation [...]'; I'm just pointing out that while that is true for twitter users at present, Twitter could experiment with other approaches if they felt like it. I'm not saying they must or they should, just that nothing prevents them. I responded in handwavey terms because your comment about 'internet citizens' seemed pretty open-ended.

But I'm trying to tell you that you'll end up relying upon user-based moderation for many cases

OK? That's the idea I was exploring. It worked to some extent on NNTP, where people would maintain 'killfiles' and different Usenet groups were more or less protective of their cohesion. I'm not suggesting it as some sort of magic bullet, just saying that centralized moderation is not the only possible approach.