It appears the Detroit News story is completely wrong

[noise]

The State Department didn't revoke the visa of foiled terrorism suspect Umar Farouk Abdulmutallab because federal counterterrorism officials had begged off revocation, a top State Department official revealed Wednesday.

Terror suspect kept visa to avoid tipping off larger investigation

From Patrick Kennedy's submitted testimony:

There have been numerous cases where our unilateral and uncoordinated revocation would have disrupted important investigations that were underway by one of our national security partners. They had the individual under investigation and our revocation action would have disclosed the U.S. Government’s interest in the individual and ended our colleagues’ ability to quietly pursue the case and identify terrorists’ plans and co-conspirators.

Kennedy testimony

There is no transcript of the hearing but the video is available on the Committee on Homeland Security website

I watched as much of the video as I could take and never saw Kennedy state that Abdulmutallab's visa wasn't revoked at the behest of US intel. Rather he stated that in some cases the visas of suspected terrorists aren't revoked because US intel wants to see where they go. Nobody asked Kennedy to clarify this conduct, i.e. has it ever backfired?