Well, yes and no. Yes, we need regulation if we want to hold people accountable for what they say online. No, in the sense that discriminating between large and small services is a bad idea. Scale has nothing to do with it, smaller services don't deserve to get off scott-free just because they didn't hit 'Twitter-scale' yet.

Again, the biggest issue here is the public misconception that Twitter (or any of the internet) is a benevolent platform. Legislation cannot change that.