It's just as I thought. You DO need that air bag switch and metal piece.
Simple to get the metal piece off. Drill out the rivets and you're done. You can go get some genuine GM rivets, p/n 92234427 at list price of $5.42 each. Or you could do what I did and go get my rivet gun out of the tool box with a box of short 5mm (3/16") rivets. Yeah, they're aluminum, but they don't cost $10.84 for 2 of them either. Worked just as well IMO. Don't use medium or long ones as you might contact the operating screw in the track.
The switch/bracket itself just unscrews with the one phillips like I said, and screws right into the new seat base. Reminder: goes on the INBOARD track. It should be easy enough.
Anyway, I cut the old blue wire for the switch at the splice in the old harness. Removed the pin from the old main floor plug. Then I spliced the short blue wire into the seat belt blue wire. And then routed the "new" blue wire from the switch to the new main floor plug. Put everything back together and tested. NO MORE AIRBAG WARNING LIGHT!!!
Works like a champ and I am D-O-N-E!! (well, except if I get a notion to replace the inboard mini-hinge cover with the correct one)
So in summary, this isn't exactly plug and play, but almost. You DO NEED the air bag switch. So don't throw away your old harness/seat right away. You'll need some stuff off of it. If GM doesn't have the proper harness, then you need to splice the 2SS heated harness like I did mine. Obviously, if I can help anyone with any further explanations, I'll try my best to help. Again, this is for a 2SS with heated leather. I'm not electrically inclined and I was able to do this, so if you know anything about wiring, it should be no problem.
Top pic shows the plug comparison. The wiring is virtually identical except for that tan wire color was changed and the new harness doesn't have the switch pin.
Second pic shows where to mount the switch and the two rivet holes on the new track.
Last pic is where I completed the air bag switch install. Now the wife is happy.