Agreed the "heart" means kindness and love, but the opposite in the metaphor from the speech is "machine men with machine hearts", which in my mind conjures an image of cold-heartedness, emotionless, robotic people.

But fascists were cold and cruel, but also highly emotional. I mean, listen to their speeches, shouting, spitting saliva, calling for raw strength, sacrifice, honor -- it's all emotion. Emotion used for evil, but not robotic.

(I think however a degree of detachness must have been needed for say, people running extermination camps, gas chambers, etc. You must stop seeing your victims as people, you must detach yourself to be able to sleep at night. But that's different to the rallies and the support for fascism from the masses; that was highly emotional).