Yes, I also noted the lack of loading docks.
One thing to consider is the economics, both Tesla and SpaceX need at lot of specialised cold-rolled Stainless Steel, even with a bulk supply contact, that might be expensive, especially if a highly-specialised formula, or process is needed.
Cybertruck needs to hit the production cost target price, and there is a lot of Stainless Steel in each body.
Hypothetically what might be needed are electric-arc furnaces, some sort of mixing facility, then the facility to do the cold-rolling. Perhaps the denial from SDI may have been cleverly worded, they seem to deny Stainless Steel shipments, but didn't necessarily rule out supplying Tesla with steel or other metals.
I'm speculating on a long shot here, it isn't that likely, but one way or another, Tesla needs to get a lot of Stainless Steel at a good price.