"Ah!" Harry said suddenly. "I get it now. The first False Memory Charm was cast on Hermione after Professor Snape yelled at her, and showed, say, Draco and Professor Snape plotting to kill her. Then last night that False Memory was removed by Obliviation, leaving behind the memories of her obsessing about Draco for no apparent reason, at the same time she and Draco were given false memories of the duel."

Since that was the last theory Harry proposed before he switched from theories to lines of attack, and nobody fully shot it down (there was an objection, but the objection was just that it'd be difficult), I have to assume that was his working theory when he left the room. And I would not automatically assume that this scenario, which we know to be very close to the correct one, would count as "innocent" in front of a wizengamot led by the angry, racist father of the victim.