Nobody gets a free pass from needing correct equipment for overwater operations. Single engine aircraft require people have flotation devices if you are farther than power off glide from shore.

are you talking about 91.509 (large turbine multi engine aircraft) only need it if you are more than 50 miles or more off shore, and even more requirements if more than 100miles.

Also this flight was operated under part 135 right? more requirements there im sure... But im not familiar with 135.