RDWHAHB. CO2 is heavier than air so it would still have a nice blanket if it wasn't disturbed. (Doesn't need to be under pressure)
On a side note, consider using vodka in your airlock.
I've been lurking for a few weeks and this forum has proved immensely useful during my first brew (Deschutes Obsidian Stout Clone). I've finally registered and looking forward to many years of delicious home brews to come.
Cheers :tank: