The political logic of the GOP is fairly coherent actually; they want to push back the government. And in that light the ACA is a red line they don't want the US to cross because it has the makings of an entitlement program that nobody in the future will be able to abandon again. No matter how rickety a scheme they have made it.
The problems of course is that the Tea Party folks don't understand that by using unorthodox means to rein in government they may be pulling the rug from under the financial system of the entire world. And once that happens they may indeed find that government is a lot smaller than it used to be. They will also find that all Americans will be a lot poorer than they are today, with little hope for recovery as the world will never trust US investments like they are trusted today again.