No, you pretty much hit the nail on the head.
I can't claim to be an expert, but thinking about my time aboard ships I do not ever recall a need for a forced air ventilation system to have fan-assisted exhaust. The air only needed a route to escape naturally.
When we would conduct fire drills we would secure the air blowing into the space and close exhaust vents. We didn't have the capacity to negatively pressirize (suck air out). When a fire was put out we would place blower fans to suck air out and exhaust smoke outside the ship.
I think you may be looking for a critter that doesn't exist by seeking exhaust fan systems.
And a ship is a veritable cave, so there are similar principles at work.
In that case, I'd say what some people are calling the generator room is actually BOTH gens and fans. Why not?
The Navy, NOAA or NASA. Prolly NOAA. If it was weaponized and meant for us, it's not so high-alt that it's out of reach of our fighters.