It seems strange that there is no exit interview or formal handover on Muir's last day, and he is able to stay there without being noticed.
shareI think what you're suppose too take away from this was that an ordinary boring last day got preempted by an unusual event. Plus, my guess is that the CIA takes longer than one afternoon (or one day) for an exit interview (debriefing).
shareHis archives and personal files would have been out and cleared 2 weeks prior. His last day would have been ceremonial ordinarily with exit briefings having happened in prior weeks and hand offs to other ops having been in transition
It was the point of the story that the easy day planned was interrupted by the Bishop event.
Ops officers then had much autonomy and it was not widely known what they were doing. They would often migrate to operations or select ops of interest based on those put up by analyst briefings.
The ways ops budgets were handled in the Congress were to provide blanket appropriations without having to line item out what the Funda were for...in covert. It gave Congress and the administration reporting to Congress deniability.