Even without that, there are solutions.
[0] I'm not holding my breath but I'll be happy if it does work out. IMO the biggest problem isn't even making them work, it's making them safe against deliberate tampering by highly motivated people with a lot of time on their hands.
The margins are razor thin, generally negative with boom years in between.
A 400m containership is operated with a crew of 16 + whatever maintenance technicians are on board. How du you feel about leaving a single low paid person in charge of the reactor on a 6 hours on and 6 hours off schedule?
The long distance shipping industry is looking at methanol, ammonia and hydrogen to decarbonize.
The way small modular reactors are advertised, that's not the risk I'm worried about.
Instead, I'd ask: what can Hamas/North Korea/literal pirates do if they boarded the vessel half way between ports, and are actively trying to cause problems.
This may be a underestimate of what would actually be involved with this change.