Agree they are big machines, but it could be that one is doing up and downlinks (rebro) for any on board cameras, or gyro mounts on camera boats. If they are running a lot of channels, the rebro machine could be full of link kit that wouldn't leave much room for a camera op and the associated gear. In the UK, Link XP make a kit that will do all of that from one box, so it is possible to receive three ground cameras I believe and rebro them with the on board heli camera too. And it will go in a 44.
Also, a linking machine will traditionally work higher or in a different position to the needs of the camera ship.