Shuttle rescue missions
I guess the expense of a Shuttle standing by for a rescue mission is not in the works.
What would happen if the Hubble repair crew experienced trouble and a standby Shuttle was launched and the rescue Shuttle became ill? You would have two Shuttles in trouble with two crews and no where to go but down. Public outcry would be devastating on the decision and Okeefe would probably experience calls to resign if things turned out for the worse.
Imagine leaving a damaged Shuttle in a Hubble orbit to only come down in an uncontrolled reentry if you managed to fix one but not the other.
It sounds like ISS is to be Shuttles repair garage and simple EVA's are not to be considered for repairs.
Just some thoughts.
SteveS