Did Diego like Lenin?

The subject of his mural was "Man at the Crossroads", and it was meant to depict modern life based on technology and sciences. The increasing amount of machinery everywhere, rapid advancement of scientific knowledge, efficient and pervasive industrial production displacing manual production and agriculture, automobiles, radios and such modern things intrigued many people in the 20s and 30s and they pondered how such changes in the economy and modes of production would affect society and politics.

Diego Rivera, being a Socialist himself, painted Lenin, other Socialists and working class people on the right side and wealthy bourgeois on the left, to symbolize the political and societal divisions created by the modernism.

The Socialists, the Capitalists (with the introduction of Taylorism, exemplified by the Ford factories) and the Fascists (especially the Italian kind) all regarded the common people as parts of the well-oiled machinery, working for the advancement of either The State, The Company or the The Working Class. The hero of the era was the industrial worker and the industrial production was at the centre of all politics.

So Rivera probably liked Lenin, but Lenin was most of all included to add symbolism and societal aspects to his study of technological modernism.