I didn't read the article closely yet and I certainly can't comment on US policy but the Canadian Coast Guard goes well out into International waters for rescues.
Now, my first thought is that they were out of range of the type coast guard vessels in the area (capacity wise). However, I would have thought they would have made arrangements with other vessels (coast guard or other) a lot sooner, not letting them drift along left to chance. I wouldn't expect them to sail days out to the middle of the Atlantic but satellite surveillance could allow them to divert another ocean going vessel in the area.
In contrast,
I recall a story when I was younger about a Canadian Coast Guard cutter that ran out of fuel because it rescued some fishermen on the far east side of the Grand Banks when they knew they were too low on fuel to get back to port so they arranged for a refueling from another vessel.
