Draco doesn’t have authority to forgive it on his own. The blood debt is said to be owned to the House of Malfoy, and Lucius is Lord of that House, and Draco is a minor.
Besides, Draco would never antagonize and publicly embarrass his father that way. Draco is also very angry at Hermione himself, now.
Here’s another idea: Draco uses his Patronus to tell the assembly he forgives the blood debt. Harry can use his own Patronus to beg Draco to do this.
Draco doesn’t have authority to forgive it on his own. The blood debt is said to be owned to the House of Malfoy, and Lucius is Lord of that House, and Draco is a minor.
Besides, Draco would never antagonize and publicly embarrass his father that way. Draco is also very angry at Hermione himself, now.