If the bumper with threaded hole is original, the skin could have been swapped from an Ex. not equipped. Or maybe the skin is the original or an identical replacement, and it's the bumper that got swapped from an equipped Ex or PIU. You'd probably have to do some dismantling to see paint colors & witness marks to be sure, but it's sort of pointless. Either change the bumper skin to give you access, or don't.