I'm not sure the defense works though. If Fanny who has barely been outside of Mansfield Park and around few people, can figure it out, then Edmond who has been away to school and traveled, has no excuse it would seem. It's like he's lost his footing and trying to put a good spin on things instead of taking the time to examine questionable situations/actions more closely. While Sir Thomas is away, the brothers are suppose to be looking out for their home and the ladies of the house. They should be taking care of who they are allowing into their home and those they do let in, they should be making sure they are being appropriate and respecting their home and family. Anything less should be unacceptable one would think. Just a thought.