My male crested does the same thing to my daughter. She has resorted to making a paper-napkin diaper for him - and wait until he has "unburdened" himself on the napkin.
We were thinking of creating a "rhac diaper" for all you who have to deal wtih our crapping critters.
My theory is that they do it because they DON'T want to be handled. I also believe that if you put them down when they crap, it re-inforces the behavior. That's why we use the napkin. I'm not sure I'm right on that - but at this moment - it is a workable theory.