There's considerably more to it than a "nice idea". It's a requirement that ships must be able to show that the ship's insurance (P&I) covers costs.
The amendments require that a certificate or other documented evidence of financial security has to be issued by the financial security provider of the shipowner. This certificate has to be carried on board the ship.
It's similar to what is already required for oil spill and wreck removal insurance. It's very common to have to show these documents to port officals. In some cases the documents must be sent to the port in advance to obtain permission to enter.
It's analogous to being pulled over while driving when the cop asks for driver's license, registration and proof of insurance, but ship get "pulled over" every time it enters port.