Per my friend in their ops center, it was due to the fact that the crew wouldn't have the duty time to go back out if they diverted somewhere else so they came back to get a reserve crew on the plane.
#qualifiedopinion
Odd.
I figure if I'm over BGR and we've got a disruptive passenger, I think the feds would question my decision about turning around to return to JFK instead of 'nearest suitable'. Unless the passenger wasn't a threat to air safety. But then, if he wasn't a threat, why did you turn around? Is a non-compliant passenger essentially a threat or an annoyance?
I know a crew that the Feds violated for having a passenger situation onboard and overflying XYZ to return to their departure station. Dispatch said it was kosher to return, but the FAA interpreted the situation as "nearest suitable".
Having started down the Feds at the big brown desk in Georgia, I'd hate to see the expression on the POI's face if I said, "With my concurrence, we agreed to overfly a number of nearer suitable airports because of the convenience of crew scheduling".
There are times under ETOPS that we may have a situation that we'll overfly the
nearest airport, because a more distant airport is more
suitable - like if you have a cardiac situation, and you land at Goose (I think) it'll just be you, a runway and a couple guys peering at you from the tower with binoculars and you're hours away from a medical facility, or just a few minutes more and be at St. Johns with a facility on-field. I may have those mixed up.
Just thinking out loud here.