well everyone was so hype about how he knows the history of konoha, but now... well you know...Of course he was quiet. His Sensei was there and talking (arguing), he wasn't going to interrupt.
1st of all Orochimaru hasnt lost interest in detroying the village, the thing is Orochimaru wants to detroy Konoha with Sasuke,NO, Orochimaru would have destroyed the village if Hiruzen hadn't sealed his hands back then. Orochimaru couldn't attack the village since that incident and now he seems to have lost his interest of destroying Konoha.