Did Yosef forgive his brothers?
Yosef then addresses the the transgression against him, and says it doesn't require forgiveness. Yosef points out that it is true that they had bad intentions toward him, but G-d had good ones. As a bad outcome was averted, so was the negative account of a bad deed. Yosef was applying the princple of crediting for intentions is only on the positive side. That is "machshava tova Hakadosh Barush Hu metzrfa lema'ase [Hashem adds on the credit of good intentions to the deed]" but not the reverse. Yosef insisted there was no bad deed on record, only bad intent, and that doesn't count by itself.