How to assassinate Dumbledore had, at some point, ceased to be Draco Malfoy's concern alone.
Especially after Snape had staked himself on it as well, Voldemort had practically given tacit approval to their operation, allowing Draco Malfoy to draw on the aid of other Death Eaters to eliminate his lifelong nemesis—Albus Dumbledore.
As for punishing the Malfoy family, that was hardly worth mentioning beside killing Dumbledore.
Because if even Snape failed, Voldemort would have no chance of eliminating Dumbledore in the short term and turning the tide against the Ministry of Magic.
That would mean an even worse situation for him and the Death Eaters.
No one could guarantee that the Death Eaters would remain loyal to him without falling apart after enduring an intense crackdown.
It had only been a little over half a year since Scrimgeour took office as Minister of Magic, yet the original Death Eaters had suffered devastating losses under the Ministry of Magic's attacks.
Even though the Death Eaters had already shifted their operations underground, the current situation remained grim. Their enemies were not merely the Ministry of Magic and the Order of the Phoenix; there was also an even more insidious and vicious Prophecy Master targeting them from the shadows. Some of the Dark wizards who had previously joined them had already fled after sensing trouble.
Though Voldemort did not care about the departure of those fence-sitters, nor particularly about the casualties among the other Death Eaters, he had to pay attention to the power he had built. Once he lost the Death Eaters' support, he would become utterly alone. When facing the vast British magical world, he would only be able to hide himself carefully like a sewer rat.
That was also the main reason Voldemort had tacitly allowed other Death Eaters to