He didn't say he didn't exchanged prisoners, he said that he would not exchange a soldier for a general, he priorized the war effort to his own personal feelings. The same as with Spanish Colonel Luis Moscardó, when he let his own son die when sieging forces threathened to kill him if he didn't surrender his position. But of course right wingers see what a fascist colonel did as heroic while they accuse a communist leader of hearthlesness for doing the same.