Again, false as government contracts unrelated to the JA are by far the biggest factor keeping US shipyards in business.
But I think the bigger issue here is the trade-off. With the JA in place US shipyards have built ~3 large commercial ships per year over the last 25 years (and the number is trending down) that are hugely reliant on foreign part/components. Without the built requirement — allowing Americans to get new ships for 1/5 the current price — the fleet would be larger and more modern. Is having fewer and older ships in exchange for assembling a few ships per year from foreign parts a good deal? What about one ship per year? One ship every other year? At what point does this not make sense?