That is only for legal protections. I'm talking about those who choose to boycott a service (again, which many people here are talking about doing with Sony) or protest against one. You can't make a law that says you have to keep someone on your staff or continue hosting content that people find repulsive. The government can't charge you with anything for what you have on your service, but they can't punish you for firing someone who is toxic enough to drive away your customers.
Safe harbor is a special protection making you immune from what you host. You should lose it if you're going to exercise editorial control and effectively become a publisher. A publisher is liable for what he publishes.
If you're liable you're liable, and will have to be more careful on what you allow on your platform, this doesn't affect just the lone 'toxic' guy on the platform but everyone on the platform. This will affect any social media platform, if they are found to lose safe harbor, these social media platforms will go out of business or embrace free speech.