Treasury doesn't set the interest rate. They offer bonds at auction, and it's the buyers who set the interest rate by how much they're willing to pay for a bond worth a set amount at maturity.
I know and so does the author. The point is that currently if a new bond were issued it would be issued at 2.67%. Another words, the treasury is looking to borrow over one trillion Dollars and yet the current rate is 2.67%. That is a recipe for disaster. At that rate it will be hard to get anyone to buy that much in bonds. It could set bonds off on an upward trajectory with nearly no end. It could create massive fluctuations in treasuries. The point is with rates as low as they on t bonds and the government ready to use them to borrow a massive amount that is bad combination.