I didn't see Jupiter mentioned in the piece, but loopy is loopy, so talking about controlling Jupiter or "the end of American economic supremacy" make just about as much sense.
The immediate reference is "doing nothing could lead to default." If the question is default, that would end the supremacy of the U.S. financial industry. The downturn from a default would be very bad news for all of us, but the end of the supremacy of the U.S. financial industry would likely be good news for the rest of us. This would radically reduce the political power of this sector and their ability to steer the government to serve Wall Street's agenda. We could instead pursue economic policies that serve the rest of the economy with the resources consumed by the financial sector redeployed to more productive uses. It wouldn't be surprising that Brooks would confuse the status of the U.S. financial industry with the status of the U.S. economy, but it is an incredibly embarrassing mistake.
If Brooks meant literally that the supremacy of the U.S. economy is at risk, then he is ignorant of data on international comparisons. In absolute numbers, China is virtually certain to soar past the United States long before the end of the decade. It already is ahead of the U.S. in a wide range of measures (including college graduates with science and engineering degrees), and will soon surpass us in most all measures.
Of course China has four times the population as the U.S., so surpassing the United States is inevitable as the country moves higher into the ranks of middle income countries. We can instead ask about per capita measures, but here supremacy has long been in question. The U.S. does enjoy a higher per capita income than most other wealthy countries, but most of this gap is due to working longer hours, not higher productivity. Furthermore, since we have much greater inequality than anywhere in Europe, typical workers do much better in most European countries than the United States. So here also, the "economic supremacy" in the article seems to largely live in Brooks' head.
In short, Brooks thinks it is important that we cut Social Security and Medicare so that he can maintain his illusions of economic supremacy. I suppose that is kind of cute, but it's not very serious policy. But no one ever said that Brooks was into serious policy.