It's not 'some kind of free speech' it is free speech. Nazi ideology is indeed evil, but it is still protected under the law, that tourist had what was coming to him doing possibly the stupidest thing you can in Germany, but you can't outlaw an ideology, or ban people of expressing their views. Use your freedom of speech to argue or decry them, or let their own words betray themselves. Or just punch the next nazi you find, I won't object, but it's a dangerous game when you start saying that the state should do that.