That statement does not make sense.
Container ships are transporting manufactured goods from China to other countries - US, EU, ROW.
If there are no shortage of container ships that means that those regions are experiencing economic downturn, not China.
Chinese economic downturns will result in "no shortage of" ships that carry raw materials.
The problem is the vast amount of pollution that those ships generate. In theory this alternative would provide the same service with far less ecological impact. Actually getting modern nuclear reactors to perform as expected has resulted in complications.