It’s about not having enough emergency workers to respond to a marine emergency. They are all patrolling to monitor compliance with the curfew and social distancing regs.
And as a diehard cynic, I have to say the government is really doing a great job managing this craziness, and the citizens by and large are almost 100% in compliance. At the supermarket they limit the number of people inside, and every keeps their 6 ft distance in the entrance queue and inside the market. They report the number of people cited for prosecution each day for violating the curfew regs, and in a country of 65,000 it usually ranges between 5 and 10 people caught walking, driving or gathering in groups of more than 2 .
But the snorkeling ban still makes no sense.