Factory black-painted handlebars? I'm no expert, but I assumed they were all chromed.
I guess an good inference could be drawn from the inside end of the location/ground screw. If it is in fact sharply pointed, that would suggest that it was designed to either 1) serve both functions, or 2) be primarily a ground screw by piercing whatever non-conductive coating might be applied to the bars.
But if it's just a locator, why make it finely-adjustable instead of a cheaper cast-in peg like on the throttle side? That does suggest it's main function was as a ground connection.