Um. They self-identify as Communist. They worked with Stalin's Comintern. Mao *led* a Communist revolution. Have you read "Mao"?
Have you ever seen a Communist state that *wasn't* a dictatorship? It goes hand-in-hand with how they work.
They can call themselves whatever they want but there is a difference between theory and practice. Communism in theory is not necessarily a dictatorship.