I understand your point but boats that sit and are not used become troublesome rust buckets. For example, raw water impellers can take on a “set” and can easily fail or disintegrate; fuel may become aged; engine manifolds corrode; batteries fail; shaft seals can go bad; diesel aftercoolers corrode; etc.
I could go on for a few more pages but you get the idea.
The terrorists might be able to run a muscle boat but when you’re running at high speeds there’s little margin for navigational error. You can ground the boat if you’re not extremely careful. Chartplotters help with navigation but many of the modern versions are multi-function and require some experience to properly use.
One other thing is that fuel consumption on large or fast boats is enormous and beyond what most non-boating people realize.
I did not go to the source article, but is it not possible that these boats were not in long-term storage and are just stored whenever not being used. Perhaps the owner uses it every other weekend.