That means the connection needs to go directly from the ground, up to a sat, then immediately back to the SpaceX ground station. That means for a while you’ll need to be within a certain range of a ground station, so international waters won’t work for a while.
The marine “anywhere on earth application” won’t be really applicable until they get the next generation of satellites with laser interlinks launched.
I don't doubt that SpaceX will figure out satellite to satellite high capacity trunk links within the next 5-6 years. But for now they are definitely proceeding with building medium sized starlink earth stations in the same general regions as where the CPE will be located.
Still, territorial waters extend for 12 nautical miles. Apparently, these satellites fly at 1100-1300 km. If ground stations (both SpaceX backbone routers, and mobile terminals) can talk to a satellite 45 degree above horizon, the satellite can connect the terminal with the ground station in a circle 1100-1300 km radius underneath (slightly less due to Earth curvature, but not by much).
Not gonna work in the middle of the Pacific, but might be good enough for many. For instance, one can sail from here across Mediterranean Sea all the way to Africa or middle East, while staying within reach of Europe-based routers. That’s assuming SpaceX gonna build them.
SpaceX updated all of their applications to only request 550 km.
Under ideal conditions you could have internet up to 1000km off the coast then even without laserlink. Under normal conditions it would be more like 500km from the nearest ground station.
I'm still hoping that they can use user terminals as ground stations for these maritime scenarios.