Mostly the principle that direct, tangible, and irreparable harm is being done by the speech. I called these "hairy" exactly because they are less clear-cut than most cases. The line between satire or speculation and slander, for example, can be kind of notoriously hard to draw, many "doxxing" incidents mostly involve finding already-public information, and incitement to violence is pretty difficult to demonstrate in a satisfying way

The reason I bring up these examples is that they are what I consider the edge cases of freedom of expression. There are genuinely difficult tradeoffs between values, but allowing stuff that bothers some people to be published is not one of them