They are going downhill fast.
I am not sure what, if any, "rules" you're referring to. But there's nothing being spoken about here that hasn't already happened and hasn't already created widespread damage, both to holders and to the credibility of the ratings agys themselves.
There is only one rule and one sub-rule, at least prior to our "new paradigm" of government interference and infinite bailout. That rule is: Treasuries are risk free, and every other debt instrument bears some degree of risk, no matter how well insured. Period. Agreeing to a higher coupon is your tacit agreement to take on more risk. Period. An immutable law, and one that worked very well for quite a while.
What the Tsy is doing now, in a series of improvised, chaotic, and arbitrary belly-dancer-on-angel-dust gyrations, is to bring all manner of debt instruments to the identical risk-free level of Tsy debt. The "bailout"; the "backstop". It is artifice on the grandest of scales, a Potemkin village, totally synthetic, and ultimately impossible to maintain.
Unfortunately, and this looks to be the next stage, and I say this with all the alarm I can and it looks to be somewhat imminent: if and when the day comes when it becomes clear that bringing these debt instruments "into" or "under the wing of" either the Federal Reserve or Tsy in an effort to upgrade their perceived creditworthiness to the same level as Tsys IS BEYOND THE FISCAL CAPABILITY of the Fed or Tsy without either the unbridled printing of railcars worth of fiat dollars or the explicit default of Tsys themselves.......AT THAT MOMENT, Tsys will assume the value of the bad debt: EXACTLY the opposite of what Paulsen/Bernanke intended, and we will see a deflationary collapse in our financial system. That is the threat. The "threat of the threat" is a big part of what is afflicting the stock market right now. (I also think the stock market is revulsed by the threat of an Obama presidency & veto-proof Dem Congress, is subject to enormous deleveraging and forced selling on the part of huge hedge funds, and is further reacting to THE BIGGEST EVER collapse in commodity prices, a full-on 1929 no-jive crash) What scares the daylights out of me is that the credit dislocation implicit by this will be without a shred of doubt the most disruptive worldwide non-war event anyone alive has ever seen. I am absolutely serious. Talking about markets closing for a week, reopening 2500 DJ points down, interest rates doubling overnight....I mean the gates of hell.