Not be churlish, but while science may not be a democracy (though I think that's kind of an open question), our government is. I think the EPA is taking the entirely sensible position that, given how economically dramatic any regulation of greenhouse gases would be, and how difficult the statutory interpetation questions are in this particular area, it will wait for Congress to take action on global warming.
Also, I would like to point out that, while my butt is indeed quite shapely and pleasant to look at, the picture is of someone else's.
If the EPA wants to claim that CO2 is a special case which shouldn't automatically be regulated under the Clean Air Act, then they should go ahead and make the political, legal, and economic arguments. They shouldn't misrepresent scientific fact just to get out of some (admittedly very) heavy lifting.