GPT4 sez: "This sentence uses figurative language, so it doesn't refer to literal meanings. "Fear" is a stressful emotion induced by perceived danger or threat. "Acute" suggests a sudden onset or intensity. "Moral priapism," a more abstract concept, suggests an abnormally extended or excessive fixated morality, much like the medical condition priapism refers to an unwanted, enduring erection.

Overall, the sentence means that fear can lead to an exaggerated or obsessive moral response. This implies that when someone is afraid, they might stick rigidly to their moral code or make moral judgments more extremely or rigidly than they would in a state of calmness."

seems fair

Edit: My gloss of the summary: "Fear creates a hardon for scapegoats among the pitchfork wielders."

Permanently aroused to look for any injustice.