If I buy a server, and a T1 subscription, create a blog and allow you post comments on my setup over the internet... and I say you cant post comments about politics because this isnt a political blog, you have not been harmed. And I certainly havent restricted your rights.
You had no right to post anything whatsoever before I bought the server, before I paid for the connection, before I setup the software and before I allowed you to sign up. What changed that gave you a right to use my platform for anything I dont agree with.
If I bought a football and asked Peyton Manning to sign it, and he wrote an anti war screed instead, would it be a violation of his rights to erase the comments and get someone else to sign it instead?
The answer is not at all. My property is mine. That is completely different from the government, because government is obligated (due to the fact that they are to in existence specifically to guard rights and take direction from the people) to accept reasonable (ethical) public input.