Those Are Really Tight Oxygen Controls, Right?

The secret is probably just carb your beer higher than you need to. And as long as your beer is cold enough and you're the pack, you'll be okay. There's nothing there, if you don't have your carb right, there's nothing you can do to prevent oxygen ingress in most packaging scenarios. But that lost CO2 there is what's giving you this actual ability to fob your beers in ways that are going to keep oxygen out.