I think you missed the fact that there was a whole week preceding the assault on Cocijo itself which a lot of players also participated in (just judging by how quickly the systems were cleared out once it got rolling) and there were no other rewards than participating in the defense of Sol and engineering materials rewarded for the clearance of any Thargoid invaded or controlled system. Quite a bit of the talk I remember hearing around then was that there were also a lot of players either new to AX or the game, or returning to Elite because of the Titan attacking Sol, asking around about how to best get involved. Not only because it was just the end of the war which generally didn't interfere too much with the game's proceedings anyway.If it weren't for the CG like rewards for just showing up to the 'goid fights, it would have passed almost without notice.
Just because you don't like it does not mean that it was not popular. Yes, the SCO drives motivated even more people to go and at least provide a minimal contribution to attacking the Titan, but it would still have drawn in a fair number of players regardless of this.