That threaded location is where the center stand for the GoldWing or F6B is bolted on. There is at least one thread on this forum addressing that modification.
I used a jack similar to yours, to store the bike over the winter. My saddle for the inserts on top of the jack are V shaped and so I used appropriate metric bolts fastened into the threaded location to serve as the jacking points on the bike. FYI, the bolt on the RHS is left-hand threaded. Hopefully the saddles are far enough apart to provide a stable lift for the bike. Also, only the rear wheel is lifted off the ground using this procedure.