Cargoships have operation costs in the 10s to 100s of thousands per h. Sure you could bring that down for what's required here, but you'd still sink a lot of money into these ships. How many maritime subscribers would there be?
$5k USD a month is significantly less than the monthly cost for any usable bandwidth allocation to a current tech ku band geostationary maritime vsat terminal, such as for the smallest "expedition" cruise ships, nevermind a big one.
