I give you points for being creative, but ultimately, your last, smaller, admission is the controlling one. S&P is not a constitutional actor, and they cannot create a constituional duty for Congress to act. If S&P said that the Bush tax cuts would stimulate the economy, and threatened to lower our rating if Congress elimnated them… would Congress have a constitutional duty to accede?
In any event, “…shall not be questioned…” is a term of legal art. It means “cannot be challenged in court.” Accord Art I, Sec 6, regarding Congressmembers’ speech on the floor: “… and for any Speech or Debate in either House, they shall not be questioned in any other Place.”
You understand, I aussme, that doesn’t forbid me from asking Rep. Moran why he gave a speech supporting Obama last week?
And it doesn’t forbid S&P from asking. And it doesn’t mean that Moran has a constitutional duty to shut up, lest I (or S&P) question him.
Although I can dream…