I don't sell travel insurance but I do send all clients links so they can purchase it, and recommend it strongly. You need an insurance license to actually sell it. They could have purchased it directly from Cayo Espanto as well but did not do that either.
At this point the clients are only looking to reschedule, not get a refund, but CE will only do that if they can re sell the space. The clients knew this going into it. Can't believe they didn't get the insurance for their 12K honeymoon (without air! - they purchased that on their own)