It's a precedent that government can tell ISPs and others what they can provide you. Once they have that in place, it's not a stretch to imagine them furthering that power for political purposes.
Think about surveillance legislation after 9/11. None of it applied to domestic population originally
It’s the opposite of that - it’s saying companies cannot discriminate – but also that argument doesn’t make any sense because governments already do that and nothing in network neutrality legislation grants new powers. If they want to ban a political party’s website they’re passing new legislation (or ignoring laws) whether or not network neutrality laws exist.
Think about surveillance legislation after 9/11. None of it applied to domestic population originally