Mao was focused on the peasants. Many of the other CCP leaders followed the Stalinist line. In fact, Mao was constantly fighting this clique for control of the party. Mao only succeeded in becoming the leader during the Long March. Even then, he had to keep fighting them off. During the early United Front period, it seemed like he might even lose out to Wang Ming. Only two things cemented Mao's leadership over the party. First, Wang Ming's faction was discredited when Wuhan fell to the Japanese. Second, after the Soviet Union was invaded by Germany, Mao purged the remaining Stalinists.
Stalin wasn't happy with Mao, but Mao was in control of the party. If Communism was going to spread in China, it meant accepting that. Usually Stalin was intolerant of any kind of deviation, but in 1945 and 1946, he was also using the threat of the CCP to force Chiang into negotiations over Chinese foreign policy in regards to Mongolia and Manchuria. So he was more than willing to give Mao aid in Manchuria while he prolonged negotiations. Then when Mao started actually winning, Stalin knew he had a good thing going and was willing to tolerate Mao's deviationism.
If you are looking at Stalin not helping Mao, you need a different geopolitical order in 1945. Probably because of a POD during the Sino-Japanese War.
If China won the Battle of Wuhan in 1938, it is possible that Wang Ming's faction retook control of the party from Mao, or more likely ended up splitting the party in two (Mao always went somewhere far away and did his own thing whenever he couldn't be in charge). If so, Stalin is likely to support Wang Ming and his supporters against Mao in postwar China. Ironically, this means most likely the KMT retains power.