Closing down a subsidiary that sells what, 30K if that, in its home market makes perfect sense to me. Remember GM is supporting their R&D, Engineering and Production for a subsidiary that produces something like 1500 vehicles per week at 60 - 70 vehicles per hour if that with overtime.
Saturn sold way more cars than that and GM assimilated their (R&D, Engineering and Production). Where is Saturn now? Can you point me to their headquarters? I do believe you will find Saturn is just a name in some GM office building in Troy, Michigan. So GM can and I think eventually will do the same to Holden as it did to Saturn, economics will force them to. I hope I am there to see it personally, that would be a dream come true for me, even better than when I watched Saturn being assimilated.
In reality there are no divisions or subsidiaries, there is just GM, what most people think are divisions or subsidiaries is just smoke and mirrors and a marketing team. "Pay no attention to the man behind the curtain" Dorothy! There is no Great and Powerful Wizard in OZ (Pun Intended), there's just GM in Detroit and it can globally brand cars there and export the designs to the world also.