Regarding the possibility a spy working for the US could have snapped that photo, that assumes two things:
- The US had a well-funded intelligence apparatus able to infiltrate spies into a highly militaristic empire with a well-developed intelligence/counter-espionage agencies with highly experienced operatives.
- That the US was able to recruit enough willing agents who could feasibly infiltrate the IJN administered South Pacific Islands and get them close enough to snap a photo.
The first has a lot of problems considering the US severely cut back on military/intelligence related spending after WWI, state of counterespionage/security within the US military in the 30s*, and the somewhat ad hoc nature of spywork in East Asia during this period as admitted by some former military officers serving in such a role in that period…especially considering funding/resources were a serious issue back then.
In short, it ascribes far more capabilities than what the US actually had in the 1930’s…especially in East Asia. Most of those assumed capabilities wouldn’t manifest itself until after Pearl Harbor and especially after the founding of the OSS/CIA.
And the second was even harder not only because the IJN administered South Pacific was tightly controlled to discourage spying attempts, there were also serious issues with conflicts with other intelligence agencies who were also trying to gather more intel on the Japanese Empire’s military who may not necessarily want to share info with the US…such as those of the then dominant colonial European nations with longer-standing wider intelligence networks especially the British Empire.
- It was so poor that a former US Naval officer cashiered in disgrace in the 1920's for financial/social improprieties was able to easily talk himself into critical areas of Naval bases/ships so he could access top secret naval plans/ship designs, have them photostatted using Navy photostat machines/personnel, and return them without arousing too much immediate suspicion.
It was only after he started to make mistakes and became disgruntled with a new Japanese handler who severely reduced his payments to the point of blabbing about his being a Japanese spy to a reporter that he was caught.