Sure, if you have a smoothly functioning business where you are efficiently turning raw materials into finished goods which are being snapped up by consumer, yeah, prioritize the high margin stuff. That is not what is happening here. All those Ses we see at Fremont are sitting on the books as either inventory or work in progress where Tesla has incurred most if not all of the material and labor costs and not recognized any of the revenue. Typically, the priority would be to get that inventory off the books ASAP.
IMO, Tesla is feeling some pressure from the competition and needs to make a statement. The "sold out" statement was for the 3/Y as there was not S/X production to sell out.