I don't think "totalitarian" is part of Marx credo. Dictatorship is not used in that sense, and in any kind, according to Marx this dictatorship is transitional and must also end.

Agreed about the "not leaping" too soon comment, though.

In the end I think Mao simply saw the USSR as the more immediate threat, and faraway rightists in America were less of a concern -- and if they opposed the Russkies, so much the better!