I've got a fair amount of ocean crossings. Shutting an engine down over the ocean is not the 3 alarm fire you think it is. Wet footprints are illegal to dispatch, so if there's a bad vibration, shut 'er down. Its better than having boats picking up pieces of human bodies and airplane parts because you let that vibration turn fatal (and yes this has happened before, look it up).
Too many people think an engine shutdown is the end of the world, its not. Losing an engine today is a far cry from Pan Am 6.

https://www.youtube.com/watch?v=FqRAOvz71B0