Regardless of what Dumbledore's plans were and whether they were defensible or not, none of that matters now because Taylor just decided that engaging the enemy today is a better choice than a complicated plan that requires inaction today to (maybe) achieve victory tomorrow.
Fact is, unless Dumbledore has far more influence than seems reasonable at this point, the Ministry is going to come down on Draco like a ton of bricks, just like they did to dear Lucy. Now, in Draco's defense all we know he's done so far is commit conspiracy to achieve mass-murder and insurrection. But that's still plenty to get him thrown into a cell next to daddy during a time of war (which the Ministry under the new Minister has finally acknowledged).
The question is what the fallout from this is going to look like. Because Taylor isn't playing this 'war in the shadows' game that Dumbledore is, and she's just announced that to the Death Eaters, Order, Ministry, and most critically, the Hogwarts students and the general public. Sure, knocking out one child Death Eater is hardly going to be war-winning, but once she starts to get rolling its going to become quite clear that there's a new and quite decisive player on the board. Everyone else is going to have to figure out how to deal with that, allies and enemies alike.