While I wish they could have found a more tasteful way to say it, it is pointing out significant flaw of many on the left, their belief that everything repugnant that anyone does happens because they don't bother to think and reason it through, so if we just followed logic, everything would be all right. Unfortunately, the world does not work in such a rosy way. The Nazis were quite convinced that what they were doing was the sensible thing to do. Doesn't make them any less evil. Indeed, I would say it made them more evil.
You're reading too far into Obama's comment- and Reagan's.
