Your example of the COMS sort of destroys the argument that standing produces a better atmosphere. With cheap ticket prices and 10,000 spare seats, do Man City really want to start banning home fans? I suspect if we had a quarter of the seats empty a blind eye might be turned more frequently as this issue seems to have reared it's head more often this season.
Yesterday, from what I could see, home and away fans were kept apart with the use of safety fences until off site, a minor inconvenience but no big issue. It's a bit more difficult with our ground on top of a hill and only two points of access. It's not that many years ago that people moaned about away fans being kept in at the end of games to allow home fans to disperse. With regard to that issue, I would argue that RFC's current policy is the best compromise in the circumstances.