At the moment boat=yes is tagged in the entire section. This could be changed to boat=no at the appropriate place. However, I would make this dependent on how long the section is closed. Commercial shipping usually navigates with a Garmin device, the nautical charts there are only updated once or twice a year at most. The route can probably be used again before the closure appears in the chart data on the Garmin device.
In my view, a constructive discussion is already underway in the OSM note, which is why I am hesitant to create a parallel universe here.