The other customers around you, might not be as brazen, but then start to think..."hey, if they let them switch seats, why won't they let my friend come up and talk to me?" Or...gee, maybe I could have a my wife come up for a drink or enjoy the sundaes.

While the OP doesn't plan on doing that; imho it just leads to a bigger can of worms for the f/a's to deal with.

I hope they get cleared on the upgrade list.