Do you know what the word 'apparently' means? I did not say 'is'. It's a logical tactic to see the strength of your enemy and picking a large and powerful ship with its supporting ships to do so since it is expected to survive long enough to determine the strength of the enemy since the Shivans have ships to spare and are not too worried with losing one super ship, though the Alliance beat them 32 years prior. So it makes sense to be careful and determine the strength of the enemy first. Maybe it was just there to scout Capella to see if it was a star they needed and to find out the strength of the forces there that might stand in their way before going through the trouble of calling in their other big buddies. Bosch might have had something to do with their actions. Who knows?
Maybe all the portals were dormant and groups of Sathani were separated from each other, and different sized Shivan forces were trapped in each system beyond Knosses 1 and were not united with each other. Maybe in the nebula, there was only one Sathanas separated from all others and no more could come in at first because Knosses 2 was not active, so they took Bosch with them to use Bosch to activate all of the portals all the way back to their core systems, and this enabled more Sathani to converge onto T/V space. Maybe that is why they captured Bosch. To re-unite all of their forces. Has that theory even been mentioned?
One other reason why only one Sathanas was present and was not with the others could have been that this Sathanas just happened to be the closest Sathanas to the Allied forces when the Alliance was invading the nebula, and it decided to go in and destroy the GTVA like the Lucifer did, but failed. So the others came instead, but for some reason did not try to destroy Allied forces in other systems. Or maybe it was trying to clear a path for the following Sathani so they could blow up the star to keep the GTVA out of their space by using the supernova to collapse the nodes and teach them a lesson in the process. Like saying 'Leave us alone. We don't want to waste time and too many ships fighting you'.
If anyone has other ideas, fire away. But if Capella was a real life event, imagine how frightening it would be too see all those ships.
Silly that V doesn't give info on all of that. What a waste if they can't even tell us what's going on and why. It decreases the storyline.