Tom Metzger was found guilty of inciting murder AFTER skinheads attacked and murdered an Ethipian immigrant. Why was it a crime after the murder and not before? Because no-one acted on it? That defies logic.
Metzger wasn't found guilty of a crime, he lost a civil suit.
In this situation, it might be possible to sue either the Nazis or the LLL agitators for damages, but that is a different matter.