A similar faster way to do the particular animation you have is to turn IK on for the hand touching the wall. That will freeze the hand at that location without Poser having to calculate collisions. Moving the body or other parts of the figure will cause the arm to bend while the hand remains at its fixed location. It will probably still have the same problems with bending.

You might want to try turning Use Limits on from the Figure menu. I haven't played much with that setting, but it's supposed to prevent body parts from bending unrealistically. I personally usually leave it off because I sometimes want a stylized look to a pose that requires breaking some bending rules.

My visual indexes of Poser content are at http://www.sharecg.com/pf/rgagnon