I don' think anyone ever said the wheels were not the same size or not possible to swap. Both are 19" X 7" and will have the same bolt pattern. It's just the offset is a little different, only 5mm I think so no big deal.
The main thing is the TPMS sensors which your dealership probably doesn't even know about. You will need to have the 8 tires removed from both sets of wheels, then have your 2017 TPMS sensors removed form the '17 wheels and bolted up on the '16 wheels, and then the tires remounted and balanced on all 8 wheels. Otherwise, I don't see how you are not going to have warning lights on your dash at all times. I think it will be flashing and give you an audible sound as well because it will be picking this up as a malfunction with the system, not just low tire pressure, so it probably will get annoying. If they will do all this for $125, you should jump on it.
Maybe someone who has put aftermarket wheels on a '17 knows of other ways around the '17 TPMS sensors.