So, it's a bag hook, minus the hook.
Maybe Tesla deleted the bag hook to lower costs. Owners might buy one in their shop. Except they don't sell one.
And did you ever see a cargo containment system, however sparse, that wasn't symmetrical? Just a bag hook on one side? Not both? Hmmm...Elon spent a lot of time on this one. If you loosen the nut, you'll see what it is for...