You don't beat an UFAI by enumerating the exploits it could use. That kind of argument is found by trying to find arguments for your particular cause.
Disagree. This line of thinking leads to the fragile "provably safe" design strategy.
History of engineering tells us that provably safe, provably secure systems aren't, because even if your proof is mathematically correct, you most likely forgot to include some relevant aspect in your model, which leads to an exploit.
In real-world safety and security engineering, you don't want to rely on a single-point-of-failure design, you want to think about exploits and faults, both to provide defence in depth and to use them to stimulate your intuition about the mathematical models you use, reducing the chances that you miss something important.
Large Social Networks can be Targeted for Viral Marketing with Small Seed Sets
It shows how easy a population can be influenced if control over a small sub-set exists.
This is relevant for LW because
a) Rational agents should hedge against this.
b) An UFAI could exploit this.
c) It gives hints to proof systems against this 'exploit'.