I think the best part is that the title of the episode is Man Walks into an Ad Agency, like this whole thing is a joke. And I mean Matt Weiner comes up with it like he does with all his other deranged shit, it serves as a macguffin to emphasize how any sign of weakness was it (Fred being incontinent last season, not having a foot, etc) for you, that the British office is effectively destroying Sterling Cooper, all dragging out the inevitable confrontation between the Brits/SC until next season by using this to keep the old Brit guy around..