Especially when you could have just fed them the grain directly:

…factory-scale insect production typically ends up relying on cereal by-products that are already usable as animal feed — meaning insect protein just adds an expensive extra step. For animal feed, the math simply wasn’t working.

The quote you make doesn't mention herbivores.

Cat food contains insect protein, and cats are carnivores. They even catch and eat insects themselves.

In contrast, cats are being fed grains which they wouldn't naturally eat.

Moreover, insects are a cheap source of animal protein.

Not all agricultural animals are herbivores. Pigs and chickens are both omnivores. Also insects are probably good feed for some species of farmed fish.

From the article looks like fish feed.

They are currently fed fish protein. I fail to see a difference.

I mean most pets are carnivores or omnivores, it sounds to me like they just scaled up before they had really found product-market fit