Whenever something dies, usually a larger predator. any nearby crawlers, mud raptors, etc. get attracted to its corpse or any blood that's coming from it, they could start a feeding frenzy and cause a potential creature hazard to the submarine if the corpse is nearby the sub.
This is based off behavior of sharks that swarm around a corpse, for example, a dead whale can trigger them to swarm around it and start feeding, usually in a pack.
I definitely agree with this, I also feel like it should be easier to remove bodies from the ship using an airlock or some sort of possible ejection system. I also had an idea of a way to prevent this which would be an occupation such as a janitor. This is of course, not a top priority for the developers but maybe at some point after they work on main things, they could add a job that allows you to clean up blood and remove corpses from the ship or put them in a designated room. This would be a job entirely for preventing monsters like the ones you suggest from attacking the ship.
Perhaps there could be a trash compactor that you could put corpses into that compresses them down into bait blocks that can be ejected some how, so you dont have to drag the corpse around all the time