The article (and articles linked in the article) says that issuance has skewed dramatically to short-term Treasuries, mainly due to demand from money market funds and hedge funds. The hedge funds are particularly worrisome because they are engaging in something called the basis trade, which exploits the price difference between treasury trading and treasury futures trading. And... there is extreme leverage involved - 10x or more.
So if the hedge funds blow up, it is probably going to create a full-blown financial crisis. The SEC is trying to add regulations to the hedge funds that do the basis trade, but they are suing to prevent it.