"Dumbledore said he did it, he told Father it was a warning!
A warning about what? Sure, evil Dumbledore sounds cool... but what's Dumbledore getting out of this apart from an infuriated nemesis?
An infuriated nemesis who now knows that Dumbledore is not only able but willing to hurt their family members... such as, say, their young only son who might just be the first student in 50+ years to have a terrible accident in Hogwarts.
Though I remember from canon that Lucius wanted to send Draco to Durmstrang instead, so he wouldn't be under Dumbledore's authority, and it was just Narcissa who vetoed the idea.
Update: This post has also been superseded - new comments belong in the latest thread.
The second thread has now also exceeded 500 comments, so after 42 chapters of MoR it's time for a new thread.
From the first thread: