Supreme court gains irrefutable credibility on its judgment when it convenes a full bench. This is a prelude to disqualify Musharraf so that there can not be two opinions on the judgment as it is a full bench judgment.
Supreme court is quite conscious of imposition of Martial Law but it also knows that in the current changing Pakistani politics that Martial Law will be shortlived. Supreme Court do not mind short term damage but it wants to clean up the issue so that future is secured. Even if Musharraf continues as Army Chief it would be shortlived as others in the Army are getting impatient for their turn and rightly so!
Musharraf's days are numbered! Neither he will be elected as President nor can he continue for long as Army chief. Once out of power on both fronts he will be hounded by the elected representatives and anger seething terrorists alike. He may have to take refuge in the US. I think the overwhelming margin of victory is only adding to his problems. It is easy for the supreme court that it is a sham election where about 247 votes out of 250 were in favour.