maybe he knows pujols has a small injury and didnt want to take the chance on playing him for only one inning and him possibly making some injury much worse that would affect his season( and cards).
not too uncommon for a player not to play.
Not a player the caliber of Pujols in that specific situation. All Pujols would have done is batted, if he gets a hit they win, if he makes an out they lose. It was one at bat and nothing more.
I agree with Ape, this was a case of LaRussa being a balloon knot.