If they can print as much money as they like then they obviously they can always make any interest payment, as former Fed. Chair Alan Greenspan himself has plainly stated.

Furthermore, the government doesn’t need to borrow money in the first place, because again, it can print as much as it wants.
So you might ask, why does our government create these treasury securities in the first place? I think the answer is largely twofold. Firstly as another tool for managing inflation. By giving the wealthy a safe place to profitably park their money, that money is temporarily removed from the real economy. Secondly because those same wealthy capitalists are the ones calling the shots in the first place, and they want a safe place to profitably park their money.