I mean that's not really a reason for your answer. It's just your answer restated.
Why should the spell override human behavior regardless of circumstance? And symmetrically, why shouldn't insults override human behavior regardless of circumstance.
Let's see how one of the characters quoted as inspirational to D&D dies :
"
The first son of Calatan asked him for a spear, and threatened to satirize Cuchulain if he did not hand it over. Cuchulainn narrowed his eyes and said, “Never let it be said that I am not a generous person,” and he flung the spear straight through the head of the first son of Calatan, killing him instantly. Lugaid Cu Roi pulled out the spear, and threw it back at Cuchulainn, missing him, but striking Laeg, his charioteer and constant companion, through the stomach. So fell Laeg Mac Riangabra, king among charioteers.
The second son of Calatan stepped forward, and asked for a spear. Cuchulainn refused, saying he had given enough to satisfy his honour, but the son of Calatan threatened to satirize all of Ulster. So Cuchulainn said, “Never let it be said that Ulster will lose its honour because of its champion,” and he cast his spear through the second son’s head. Lugaid Cu Roi pulled out the spear and threw it back at Cuchulainn, killing the horse, Lia Macha. Cuchulainn fell to his knees, and wept over her. So fell Lia Macha, king among horses.
The third son of Calatan asked for a spear, or he would satirize Cuchulainn’s family. Cuchualinn said “Never let it be said I brought dishonour on my family,” and threw the spear through his head. Lugaid Cu Roi pulled the spear out, and threw it at Cuchulainn, straight through his stomach, spraying out his intestines. Cuchulainn, mortally wounded, had only enough strength in him to crawl to a nearby lake for a drink of water. His enemies hung back, afraid that he had more strength than he was showing. The water revived him somewhat.
"
Repeatedly insulted into doing something self-destructive.