Asimov is weirdly dismissive of Orwell’s experience in the Spanish Civil War and the Anarchists who faught in it.

He also turned left wing and became a socialist, fighting with the loyalists in Spain in the 1930s. There he found himself caught up in the sectarian struggles between the various left-wing factions, and since he believed in a gentlemanly English form of socialism, he was inevitably on the losing side. Opposed to him were passionate Spanish anarchists, syndicalists, and communists, who bitterly resented the fact that the necessities of fighting the Franco fascists got in the way of their fighting each other. The communists, who were the best organised, won out and Orwell had to leave Spain, for he was convinced that if he did not, he would be killed From then on, to the end of his life, he carried on a private literary war with the communists, determined to win in words the battle he had lost in action.

The Anarchists were consistently under attack from the Communists, having to move troops from the front lines fighting Franco, to instead deal with Communist raids upon the anarchist communes, until they could be convinced to cooperate again as Franco would win some other battle against the weakened socialist front.

The communists then really did eventually go full ham into betrayal mode, declaring the Anarchists and Trotskyists secret fascists helping the enemy, and rounded them up to be imprisoned or killed.

It is no wonder why all that would deeply sour Orwell on Stalinist communism, and why he would write so fervently in warning of it.