Mao's estimated "kill count" is between 50 and 70 millions people.
How is that "much lower" than the US in the last 50 years? And how is that comparable? You can't compare a country with lots of different governments, politics and wars, with one dictator who managed to do this on his own in a far shorter time.
Trying to excuse Mao, surely the greatest murdered of all time far above Hitler and Stalin, is unacceptable. What's the next step? "Hitler was actually a cool guy if we compare him to the previous 2000 years of atrocities in the entire world"?
That kill count is highly inflated, under Mao China's population also grew from 546 million to 916 million and life expectancy went from 43.8 years to 61.7 years. I'm not saying he was great but he definitely not as terrible as most people think he was and he definitely wasn't worse then Hitler or Stalin.