On a
Spezial-pävention level putting senile people in prison has 0 effect.
On the other hand on a
General-prävention level it could work towards
affecting the masses.
But I can imagine that when you've been sowing the seed of guilt in a certain population for years, that sooner or later you will start to get a defensive and rebound reaction amongst those who are not guilty for the crimes of their grand-grand-grandfathers.