When Draco and Potter had first appeared in the appointed clearing to meet with the rest of the Order, Shaklebolt and a few other Aurors Draco didn't know, had been ready to bind him and silence him for good. (A small part of Draco had been prepared to let them for only a brief moment, right before Granger's face flashed before his vision.) It was only because Potter stepped up and wholeheartedly vouched for Draco that they had reluctantly backed down. Their scowls didn't diminish though. If anything, they only grew once Potter started to explain their plan.