I am a fan of any appearance of the ‘hoisted by his own petard’ construct, and not for reasons of schadenfreude (though in this case there might be a little).
The argument is innovative. It’s important to note that the opposition to the argument reported here is organizational in nature, not legal. This seemingly innocuous legal brief becomes the catalyst of their own destruction in the act of proving both the value of keeping one’s mouth shut and the failure inherent in a posture of constant aggression. The aggressor will eventually inevitably overextend himself: say or do too much.