My impression of Eliezer's model of the intelligence explosion is that he believes b) is much harder than it looks. If you make developing strong AI illegal then the only people who end up developing it will be criminals, which is arguably worse, and it only takes one successful criminal organization developing strong AI to cause an unfriendly intelligence explosion. The general problem is that a) requires that one organization do one thing (namely, solving friendly AI) but b) requires that literally all organizations abstain from doing one thing (namely, building unfriendly AI).
CFCs and global warming don't seem analogous to me. A better analogy to me is nuclear disarmament: it only takes one nuke to cause bad things to happen, and governments have a strong incentive to hold onto their nukes for military applications.
What would a law against developing strong AI look like?
r/Fitness does a weekly "Moronic Monday", a judgment-free thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. I thought this seemed like a useful thing to have here - after all, the concepts discussed on LessWrong are probably at least a little harder to grasp than those of weightlifting. Plus, I have a few stupid questions of my own, so it doesn't seem unreasonable that other people might as well.