The moment Bush pulled the gun on Sherlock, his Sherlock, John saw red.
"Mr. Bush," he said, his voice sound firm and menacing. "I strongly recommend that you lower the gun, or I can assure you that I will make sure you will never be able to fire one again," he said. "I will not stand for anyone threatening Sherlock. You could try to ask the last man who did so, but it would be difficult since he is dead."