haha, You have a point but still - the commodities are limited and we have to work with what we have.
FLstats info:
-Aluminum is very resistant to corrosion and possesses a low density, is nonmagnetic and nonsparking, and is a good thermal and electrical conductor. Aluminium is extremely important in the composition of various alloys essential to transportation, construction, and aerospace applications.
-Hydrocarbon mining is key to the industrialization of the Sirius Sector as it provides the raw materials for the creation of the Ship Hull Panels and Optronics, upon which modern society depends.
Since Southampton have a new look in RP it have 2 small refineries to help the raw materials to be easily turned in to alloys, ship panels and stuff like that useful for ship building. That is why the "Armor plating" stage is simply to deliver more goods, complete and incomplete. Aluminum is one of the incomplete materials same like Hydrocarbons (15k+15k = ~15k solid alloy and upgraded metal for panels)
Ablative hull armor are primary material for "ship hull" - 30'000 means a lot considering they are wide and huge armor plates not a tiny version.