They don’t care specifically which one that you bought.
They want the names so they can send them threatening letters saying that they purchased an illegal gun, they have proof, and if you don’t surrender it they will take you to jail.
It’s not an illegal gun.
The solid fire-control cavity is built first and the rest of the 80% casting is made around this “core” specifically so that their product at no time could be considered to be a firearm.
HA! That is genius, and probably why that particular 80% lower pisses them off so much. If the polymer fire control cavity is made first with a different color polymer the final casting can probably be subsequently cored out with merely something like a dremel tool or a drill and fine files. The operator merely needs to stop at the show-through of color from the outer casting and fine work that so the subsequently installed parts work smoothly. Damn, now I want to get one just to check it out!