No. Sylar! [John hears the pounding of feet and he can guess at where this is going. Sherlock is a fighter, but he's not exactly in fighting form right now, his head out of the game of it with everything that happened. Whether anyone can hear him now, John starts shouting.]

Don't hurt him! Don't you dare hurt him. Sylar, you're a killer, but you're a bloody pragmatist. Don't do this. I will tell every single person who and what you are if you hurt him. You'll be a pariah, just as bad as the Joker, hunted by the Avengers and Batman and every other person you don't want. You won't be able to help anyone anymore.