LeMay was a tangible threat to the Soviet Union, which had long been very scared of America’s bomber fleet, because from the end of WWII to about the mid-1960s, nuclear missiles were just not good enough, or common enough, to rely on.
So the Soviets told their American traitors to destroy LeMay with character assassination.
And that's what they and their "progressive" successors have done and are still doing. Prime example: Sen. Joseph McCarthy.