Some people sincerely believe in Communism, in Jihad, so purpose and sacrifice can indeed be corrupt due to morality and perceived obligations, duty. But when you find a repeat offender, you do not need moral obligations, or ethical considerations, you do not need an excuse - you know that he will offend again. Everything else is taken out of the equation, and the only thing remains is stopping him.
A chance at rehabilitation is of course an option, but not when illustrating a point LOL!
