One thing I never hear people (Including helicopter Ben) talk about; the willingness of other countries (
China most notably, Japan is somewhat more polite about it) buying up US (and EU) debt. Sure, they have to keep buying it (to a certain extend), as their economies would falter immediately if they would stop doing it overnight, but I'm afraid the roaring 90s and 00s are never going to come back.
So, Ben can print all the money he wants, once the buyers of debt feel it's enough to be paid next to nothing for buying up funny money debt, he's bound to do something about the income situation of overseas institutional investors; raising the interest.