he observatory is designed to observe the sun, but it would see other things as well, asteroids, satellites, the ISS, jets, things like that. If a foreign actor managed to put software in the computer system to feed information back to that country it would extend their survailance capabilities. From a scientific basis, it would also enable their science programs at little or no cost. Think of Child Porn as an avenue to download malware into the tracking and observation system of the Observatory.
If you want to be prosaic, monitoring of electrical usage confirmed that the Astronomers were running a Pot growing farm in the subterranean observatory tunnels and that was the reason for the raid.
If you wanted to get crazy, perhaps there was an unauthorized fusion lab in the basement and the FBI was stealing the technology! Or, someone was using the observatory as a quantum entanglement tele-tranporter site with a door whose far-side opened up into a Chinese Lab /strip club. Maybe they were harboring ExTerr Aliens in buckets in the under-observatory?
Numbers 1 and 2 are possible. The others just for the SciFi effect.
Naw, I'd know if my Doctor was there with the TARDIS! so I agree, the sci-fi thingy can't be right.
Or, if you take the story at face value, the janitor was there for the high-speed internet. An astronomical observatory these days would certainly have at least a gigabit, perhaps 10 gigabits of bandwidth. That kind of bandwidth would make it much easier for a janitor to build a child porn collection.