Jack Lew, US Secretary of the Treasury, seems to think bureaucracies can solve all problems. There is no need to impose an oversight bureaucracy on Puerto Rice. Puerto Rico does need to restructure its debt. It needs to sit down with its creditors and come up with a plan. If they cannot get a voluntary debt restructuring done, then bankruptcy is the only (and the correct) answer.
There is no need for the US national government to be involved at all, other than permissive legislation that would permit Puerto Rico to go bankrupt or to do a workout on their own hook with their creditors.
The American taxpayer should stay far, far away from this. Puerto Rice and its bond buyers did this on their own, freely on their own. If bondholders were stupid, then let them pay for their stupidity. Someone in Des Moines, Iowa bears no responsibility for this.
If the bonds had paid off, bondholders would have been winners. The bonds are not going to pay off, so bondholders should take the hit.