It appears AC is adopting the protocol followed by other STAR carriers, or at least UA. I recall once waiting at NRT for an at-gate SWU upgrade to clear -- had been upgraded on previous segments, but could not be confirmed on NRT-SIN segment until boarding. As usual much chaos at the gate with hords of 1Ks and PEs waiting for their version of the MPlotto. When going to the desk to pick up my now-confirmed in C boarding pass (I was SE at the time, or STARGold) overhearing an agent explaining to the male member of a couple that he was able to get his upgrade now, but because his companion had no status, she would unlikely receive hers as there were many elites ahead in the cue.

This will certainly strain a few relationships if upgrades cannot be confirmed in advance at the elite upgrade window.