I think the idea is that a "good" person can still have a (small) rate of criminality. If you kill after one crime you'll kill many good people, if you do so af

I think the idea is that a "good" person can still have a (small) rate of criminality. If you kill after one crime you'll kill many good people, if you do so after 2 you'll still kill good people. But the odds of a good person committing 3 crimes are low enough to go for it.