It would seem to lack judicial temperament to look disparagingly on him out of hand, but it's a no-brainer to me:
1. Would he prosecute the President's men for torture and illegal wire-tapping?
Not likely to the point of being 'remote possibility'.
2. Would he feed information about the 'GWOT' to the Giuliani campaign?
Probably.
It's a serious concern.
Did you notice that Giuliani used a line about having defeated "23 attacks" on the USA in the last debate?
Being incrementally informed on the facts of the 'GWOT' could tip the election in a Presidential debate. It would be an unleveled playing field that is not acceptable.