Well not sure where the disgust for jellyfish is coming from but there isn't really much of a moral argument here. What you are saying is akin to: look you just ate a burger, what's next–the holocaust?

(The organisation of the functioning of bodily orifices of the organism isn't really at all relevant for that. One might also add, that in the case of the burger, there might actually be an argument for some structural analogy that depends on the origin of the meat in a process of captivity and killing, that is organized in an industrial fashion..)

Vegans actually do say that but I get your point, not sure what the parent is getting at either, if jellyfish were to have the intellect and dexterity I still wouldn't see why they'd build camps.