I agree and there is the quandary. Rates need to rise, but not so fast as to displace the momentum in the economy. Since the momentum is really week by far the safest thing is too keep on QE'ing. The only thing I would worry about if I were him would be markets over heating on liquidity. The only market even approaching this is the stock market. But for now - green light.
When he started this game, he probably realized the unwind could be tricky. If he didn't, he does now.
In a way, it's similar to the slow debasement of the currency that's gone on for decades now. We can do it, just not too fast.