"Yeah, I know," said Angelina, pulling out her wand and flexing her arm. "But she's pretty good, actually. Nothing on you, of course," she said, throwing him a very dirty look, "but as we can't have you ..."
Harry bit back the retort he was longing to utter: Did she imagine for a second that he did not regret his expulsion from the team a hundred times more than she did?
Harry Potter and the Order of the Phoenix
I'm not sure if I got that sentence in bold correct. Did Harry think she should have imagined that he did not regret his expulsion or something? How should we understand it? What does it try to convey?