Firstly, it doesn’t matter if humans wouldn’t want to eat them because they form a part of a food hierarchy that’s disruption ultimately damages humans. It also causes a cycle in which less wild fish is available and more must be farmed. Secondly, if you read the article you’d note that people do rely on those fish as a food source.
It’s clearly a zero sum system. Every farmed fish consumed by humans is one less wild fish caught and taken out of the food chain.
Would you also be concerned if there were more whales in the ocean? Because they eat literal tons of phytoplankton which is also a food source for other fish. I think you’re just refusing to see things logically.
The idea that you can reduce the complexity of global fishing, farming and marine ecosystems to a zero sum system is flawed. Whales cycle nutrients when they eat phytoplankton and aren’t comparable to human activity, you’re just trying to divert the argument to something unrelated.