The fact that this historic camera (quite possibly the most famous of all time) was evidently not missed and unaccounted for seems very strange. Why did no one in the vast bureaucracy of offices within the space program not ask where it was? One would think that at least the Air and Space Museum would have inquired about it before. It seems like such an obvious artifact of interest.
My impression is that everybody thought it had been left aboard the lunar lander, which eventually crashed on the moon surface after the mission. From the collection of stuff, it looks like Neil basically grabbed everything that wasn’t “nailed down” and didn’t functionally *have* to be left behind.
I believe that it was most likely thought that this equipment had been left in the pod.
Good question however many appear to be from the lunar lander which, if I'm not mistaken, was separated from the Command Module before the return to earth. So no one expects these items since they're supposedly in lunar orbit -or crashed on the moon. The lander was being ‘thrown away’ and he grabbed some momentos.