It has absolutely nothing to do with his deeds (Stalin, Mao, Montezuma, etc. have been in the game)
When Hitler left power, Germany was in a worse position than when he entered power. That is really the only thing that affects this decision.
There is no reason to have Hitler as a leader of a civilization when he failed at doing so.
If Hitler had never invaded Russia and somehow made peace with everyone (even if he returned non German lands), then I could see him as a leader for (finally) uniting germany and Austria.
Doesn't hold up. Look at Montezuma, Alexander, Napoleon.