Oh my gosh! I knew they were setting it up! Also on "A sign of Three" Sherlock says that if he were to kill John it would be by poison because he has effectively managed to slip many things into his drinks for experiments! It is cannon!
I always feel sorry for Draco. Sure he was mean, but he couldn't kill. He was too nice to kill anyone. But everyone still views him as a villain, and it pains me. Because he never wanted to be like this. It's all his jerk parents fault.