This is why free speech is so hard to maintain. There are so many cases where you want to ban or censor something obviously repugnant, but once the power is created to do so, it will be abused, probably as soon as someone you don't like is now in charge.
"Permitted" is a strong word for activity enabled by a protocol. It implies some moral acceptance from the ones who designed the tool. I think a better word would be "possible". Similar to how e-mail makes it possible to send all kinds of content.