This happened to my brother, and I think it might even have been business/1st class (bigger seats but the guy still spilled over). My brother had to stand, flying across the nation, other than for taking off/landing.
Did your brother not know that the Flight Attendents have to be seated during take-off and landing?
See post 8. That being the case, why would he stand when he could have sat in their seats as they worked the aisles?
BS.