I think DIBO is on the right track - my flight was on the 19th, and the route I observed was consistent with what's shown on the bottom map. I doubt ETOPS played a factor - A350 has at least 180 minutes and besides going further south would make most potential alternates more distant, not less.
I just expected to see a route similar to the top map in DIBO's post, not the bottom that we apparently actually flew.
I was a little disappointed that we didn't fly closer to Alaska - some of the most spectacular stuff I've ever seen on a commercial flight was flying over southern Alaska on a beautiful clear day with all the snow covered mountains and ice flow spotted ocean. Then again it was pretty overcast so I wouldn't have been able to see much regardless.