Yes Paul, this is a debt spiral

Paul thinks the green line, debt/ngdp, is not rising.

These days that rate is well below 3 percent even when the economy is near full employment. Meanwhile, we think the U.S. economy has an underlying growth rate of maybe 2 percent, plus 2 percent inflation – which means 4 percent nominal growth.
What this means is that debt doesn’t spiral. On the contrary, it tends to fall as a share of GDP unless the government runs large primary deficits.

The bolded text is his mistake, he is likely using the one year rate which is at 2.5.  

But the real rate is the ten year rate which Congress pays.  The blue line is the real rate we pay, interest charge / total debt ( including the trust funds). The red line is the ten year rate, the two track, we pay the ter year rate.

The timeline clearly shows a debt spiral, the green line continually rises.