I'm pretty sure Sen. Geary was a member of the committee, and probably through no choice of his own. He asked his obligatory questions & at Michael's appearance made his statement and promptly exited because as a result of the prostitute incident he was most definitely owned by Michael Corleone.

He had to act accordingly to both save face in the Senate and also not rub Don Corleone the wrong way. You can see in his expression at a certain point in the hearings that he was not at all happy nor proud to be in the position he was in.

While he certainly gave Michael a bit of a hard time at the beginning (asking that enourmous price for the gaming license and smugly demanding never to be contacted again) and did say aweful things, Geary did not exactly betray and eventually was made to fall into line. Therefore he was never really and 'enemy' and not subject to 'elimination'.

Plus as moustachepete indicates...it's always nice to have a U.S. Senator in your pocket.

Apple