This is a tired old argument and it isn't convincing or effective. There's a big difference between having a conversation in a corner at a rock concert, and having a conversation in an online service hosted by someone else outside of that conversation, in a territory owned by a state where the host has to comply with laws which place the accountability of user-generated content on the host. A more apt comparison would be... I don't know, I actually don't have any idea. How about simply not being deliberately offensive or hateful or using whatever rhetoric that could ultimately translate into real-world violence?