Krugman still excited about the number zero

He thinks that he has discovered something about the number zero which he calls zero bound. The idea is that the short term rates have dropped to zero and that is significant. 
Significant of what exactly?

DC is debt bound as we see from this chart. The red line is DC debt as a percentage of the economy. the blue line is the ten year rate, the price DC pays for debt, while the green is inflation.  So what is happening? Government cannot spend because it has rollover disease, any more increase in the deficit and both the current deficit and past debts all raise the interest costs for the government.  Hence government has to be very careful about running larger deficits as that multiplies the interest costs.  If Krugman would read the latest research by Chris Sims, his colleague at Princeton, Krugman would realize the Congress would fail miserably it interest costs were raised up to 30% of the budget.  In fact, I think 15% of the budget is about all Congress can afford with its obligations. Hence, DC, which is the main cause of inflation, cannot afford any more spending without crashing the economy.

Let me name the problem Krugman has found.  The Reinhart-Rogoff disease, the Rollover disease, Bankrupt Congress, Hyper Republican Keyesianism,  or perhaps we should just name it the Krugman Boo Boo.