The efficient miracle of crowdsourcing has answered my question: who was running covert operations in the CIA’s Mexico City station in 1963?
First, one reader found a less redacted version of the document, revealing the person in question was an “Asst.” with 14 characters in his/her name. Speculation ran to a CIA officer name Gunnar Beckman.
Then another reader found an even less redacted version of the same document, which confirmed the speculation.
Beckman, whose name was unknown to me, was a former journalist turned spook. He was never interviewed by JFK investigators, as far I know, which is odd. He might have been able to shed light on the actions of David Phillips around Oswald’s visit.
Beckman died in 1999, which begs the question, why was his name redacted in 2018?