FYI, ships are generally safer at sea than in port for large storms like hurricanes.
I'm not sure what else I can say about this. The image of all the ships "near" hurricane Maria in my last post should be all the evidence needed to prove my point that ships can maneuver around hurricanes.
As far as whether it takes more time to deliver disaster relief with trucks vs ships, keep in mind that each ship holds thousands of containers (modern cargo ships carry 4,000 - 18,000 containers), each of which is equivalent to a single truck. I think the notion that ships are some impediment to delivering supplies after a hurricane isn't true (or perhaps more accurate to say it's a minor impediment and if that's what you mean "in small part" then we're in agreement) at least compared to trucking in supplies on the mainland.
I think the larger issue of getting supplies delivered on either the island or the mainland is actually the roads. If they're damaged, flooded, blocked, bridges out, etc., then it's much harder to get supplies where they need to be and that affects the mainland and the island equally. Although you could make the case that since PR is mountainous and restricted by ocean, there may not be that many routes to get around blockages like there would be on the mainland, but that's after the ships have arrived.