This logic seems pretty strong. From a reader:

Jonah,
The only reason why bringing Hitler to the here and now, in order to study, is that in the here and now, Hitler would not be that dangerous. The few adherents that he has left are extremely marginalized. Just calling someone Hitlerian, or a Nazi, is one of the worst insults available.
In 1945, keeping Hitler alive, anywhere in the world would have been a very dangerous proposition.
If we could have found a way to project Saddam 60 years into the future, I would not have objected. Short of that, killing him was the safest option.