How about changing efficiency module recipe

[thekoreanseal]

Why would it use spoilage if there is carbon fiber or bioflux?

[eugenekay]

It’s about the Game Design opportunity, not just “what makes sense”. Spoilage is initially seen as “waste to be thrown away”, then it becomes semi-useful as a burnable fuel. With the introduction of Biological ingredients for advanced products it becomes necessary to produce Quality Spoilage purposefully in order to scale these Modules; so Spoilage is now a full-fledged Ingredient!

Or you can pretend that Efficiency Module 3 works by Mushroom Magic.

[mmmPI]

Many players will have to "deal with their spoilage accumulating", it's part of the game. Offering a receipe that uses spoilage as ingredient is part of the tools available for the player to achieve this.

That's 1 reason i can see.