I wish I had some time to dig around a bit for info, but honestly this question immediately made me think of D1. The Cabal had been staging from there and planning the assault at the beginning of D2 whole time, right? Maybe they finally got what they needed from the computers on Mars to plan and execute their attack.
I agree the Cabal we're clearly gearing up for something big with the size of the base, of course the question is an assault bon Earth or the consolidation of Mars before the assault on Earth.
One thing, what Mars computers are you talking about? Rasputin wasn't controlled by the Psions and neither was he tied into the Tower satnet even if they could have gleaned anything.