What specifically concerns you with oxygen exposure? Oxygen doesn't actually cause problems with off flavors with lactobacillus. And brettanomyces scavenges oxygen during its growth phase, so acetic acid is not a concern. Oxygen can cause a problem with spoilage bacteria, but if you're using a chiller, you've most likely boiled the wort so contamination shouldn't be a concern.
Oxygen exposure is a bit of an outdated concern with pure cultures. I think people fear it because of the problems it causes in a sour mash. But there are so many microbes at play in a sour mash, that will not be present if you're using lab cultures and practicing good sanitation.
Even with spontaneous fermentation, the wort will get plenty of oxygen exposure in the coolship. But controlling your wort pH will more than likely prevent any problems from bacteria growing in the aerobic environment.