Thanks rankourabu.
Whew, I was getting worried.
I get it now.
Basically the I and O buckets are for the same seats and as you said because both buckets existed the Business booking was valid. If that Business bucket wasn't there, I would have been forced into either selecting Economy for that segment or pay the F redemption rate.

We just did a trip to Kauai this fall booked with the pre July redemption rates.
Flew AC in J to SFO, UA to LIH. Reverse on the way back. Had to use an F redemption to get the availability. Cost 80000 each.
And to think I got both of these new tickets for only slightly more than what i previously paid for one (90000), with better routing in my opinion. All AC J thru YVR on the way to HNL. UA Domestic F to ORD, AC J to YYZ.

And I came across it by sheer accident before it hit the blogs, just dreaming about going back again and punched in some dates to see availability and went ...? Business class is the same price - lock it in!