How to assassinate Dumbledore, I don't know when it is no longer a matter of Draco Malfoy alone. Especially after Snape pushed himself up, Voldemort almost acquiesced in their actions, allowing Draco Malfoy to use the power of other Death Eaters to get rid of his lifelong enemy-Albus Deng Bullido. As for punishing the Malfoy family, it was nothing compared to killing Dumbledore.