1. Your employer has the right to block sites and applications on their network that you use at work. Why should your ISP be different?
2. Property rights are just as important as rights like free speech and due process.
3. If I expend effort, capital, and time to make something, I expect to be able to use it, sell it, lease it, or rent it the way I see fit. 50.1% (or 10%, 75%, or 99.99%) of my neighbors should not be able to simply take away my right to use, sell, lease, or rent my property just because they don't like the way I am doing it.
4. Putting rights up for a vote should be abhorrent to anybody that actually cares about rights.
5. Where did they sign this? If they signed an agreement with their upstream provider saying "we won't restrict downstream clients in any way", then by all means hold their feet to the fire.