@Cycloptichorn,
I don't know how okie will answer, but my take on it is that they attempting to influence the political landscape.
The warning is based as much on S&P's belief that there is little to no chance that the debt crisis will be addressed before the next presidential election.
The question is whose position are they supporting, the Republicans' or the Democrats'?
My sense is that it is the Democrats' position that the debt ceiling needs to be raised irrespective of whether or not a deal can be cut on spending and taxes.
Both parties though can and will use the warning to their own advantage.
Guess work at best though.