That's neither here nor there. The original question is about seat assignments. Upgrades on partners are not and have never been an alliance benefit, nor an aspect of the preceding UA-US partnership, and neither is Economy Plus (for which US Airways has no meaningful equivalent), and I find it hard to believe US Airways would instruct its CSRs not to give seat assignments if a UA frequent flyer number is on a PNR out of some misplaced butthurt.