Of course, the lines as always get blurry. To use a random example that comes to mind, when Kathy Griffin posted the severed head of Trump - was that a direct call to violence? That's a tough one to answer. My first intuition is that it does cross the line, but I could very easily see an argument that it's not.
So unfortunately there will always be that difficulty, unless we committed to an absolutist position of not removing ANY speech. I drink a lot of the kool-aid, and even I don't go that far.