It's great to see them do something interesting while they're already in the air burning time/fuel on the new engine testing. The test flight would have occurred for the same duration regardless of the path. They needed a flight that was about 19 hours long for extended operation certification purposes.
It's a test flight, so you want to keep near some sort of airport in case something goes wrong. So yeah, you could duck over the ocean, but you really don't want to be flying in areas that could be problematic for too long in an untested plane.
