A couple of people PM'd me after this to ask about BA segments - rather than replying one-off:

There weren't any BA segments on my trip, but I could still open up the booking in BA MMB - I had one small necessary AA segment, which credited as spend pro-rated, which I guess is indicative of the way BA segments would land. But given BA and AA have huge surcharges, and now the TP/Avios credit is minimal, I'd avoid them wherever possible. There are enough codeshare options that booking w/ a TA might mean you could maybe fly BA/AA metal if you needed to and get QR or another airline with better nTPs. Feels like a good way to avoid some of the nonsense given there's no longer a minimum BA segment count for Gold