Being a team guy
I'm sure Craig Biggio didn't want to take the spot light off teammate Morgan Ensberg's first career 3 home run game, so he didn't get hit by a pitch. It would have been pretty embarrassing when the beat writers gathered around Ensberg and asked "What do you think of Craig Biggio getting hit by a pitch for the 261st time?", so number 7 stayed out of the way so Morgan could get his time in the limelight. 261 will have to wait on deck.
Not only is today an off day for the Astros, it's so off that Craig Biggio has never been struck by a pitch on May 16th.