Actually, all you should do is respect someone's right to hold an opinion. If the content of said opinion is stupid, you have the right of response to say "Hey, you're a fucking moron!" as many people have aptly demonstrated. Someone saying "Take this secret down, track the IP of the writer and cut off their typing fingers," would be crossing a line, but just as they have a right to be an idiot, we have a right to call them an idiot.