I have 2 questions:
If we stir the primary to introduce oxygen, why doesn't stirring the wine later to degas not introduce oxygen?
How about these headspace eliminators instead of topping up? Obviously you would need some sort of vacuum pump to use them but they are never mentioned when this topic comes up.
View attachment 61605
Stirring your wine does expose it to oxygen, we count on lots of CO2 being emitted during degassing to help protect it. Also, the sulfite that you have added, or will add shortly after degassing, will scavenge the oxygen out of the wine and protect it from oxidation.
Some folks use the headspace eliminator instead of topping up or selecting properly sized vessels, and report good results. Personally, I find that it's much easier to just rack down or top up and keep the carboys full, it's not like you're wasting any wine, you still will get to drink it.....................