Because retributivism held one person to be responsible for his/her actions, therefore ensuring free will. I believe in free will.
This is an intrinsic difference within the mindscapes of Dr. M and Rory. The latter was testified by Jean-Paul Sartre and John Calvin. Moreover, let's see what Isaiah Berlin has said:
The essence of liberty has always lain in the ability to choose as you wish to choose, because you wish so to choose, uncoerced, unbullied, not swallowed up in some vast system; and in the right to resist, to be unpopular, to stand up for your convictions merely because they are your convictions. - Freedom and Its Betrayal