Michael Sigman: Isn’t it precisely the job of political, financial and religious leaders to imagine disasters and then prepare for them? (Plausible ones, that is, as opposed to, say, anti-asteroid Republican Congressman Dana Rohrabacher’s crusade for funds to combat “objects coming from space that could cause colossal loss of lives on our planet.”) And if their imaginations fail them, and us, shouldn’t they be held accountable — morally and, when appropriate, criminally?