I don't see how/why it would change the O-swing%? That rate is what it is. Pitches are classified first as in the zone or out. When it's out of zone, regardless of how many in or out he sees, he's swinging just over 26% of the time. What I think would impact O-swing% would be the "Pitch Type" frequency. Swinging at FBs out of the zone is more excusable than swinging at breaking pitches, IMO, as their trajectory is easier on hand-eye coordination. Since he sees a good amount of FBs, this may account for him being slightly less selective than average.
Of course, they don't break down pitch types into averages, so doing the exercise of finding correlation between O-swing% to FB% would be a time consuming endeavor, and I just don't care that much about it.