I don't know about that.

Buying some filtered animal-derived blood plasma on the open market and letting the tissue grow/soak in it, would likely be a lot cheaper than precision mixing+dispersing of thickeners + reverse-pressure-gradient tissue impregnation of those thickeners. Food-grade blood plasma is the lowest-demand animal byproduct there is — it's what gets rejected out of even blood-sausage manufacture.

Same with collagen vs., specifically, carrageenan — collagen's cheap in bulk and works great for getting animal cells to stick to it; carrageenan's expensive, finicky to work with, and there are concerns about the carcinogenic effects of its long-term consumption. Many food-product manufacturers have moved away from previous formulations containing carrageenan; companies are only sticking with carrageenan at this point if there's nothing else that works within their constraints. Judging by other carrageenan-containing products, those constraints are probably something like "plant-derived; solid at room temperature; melts in your mouth; decent compressive strength, yet tears easily under tension."

And vegetable oils would be cheaper than animal fats... but vegetable oils with the same set of health guarantees as salmon (i.e. "omega-3 rich" vegetable oils) are not. And their product does claim to have the same health benefits as real salmon; so presumably they are aiming for that omega-3:omega-6 ratio target, since it's usually the headline "health benefit" of eating salmon. Which means they're probably buying, continuously-measuring, and mixing different oils to hit that ratio — similar to what orange-juice processors do to create a homogeneous juice.