Everybody is an "aviation expert" until the Lavatory backs up! :-)
I hear all you experts analyzing the RA maneuver, or the lack of by the United 'Guppy.'
At airports like SFO, with parallel visual approaches in progress, but still under positive radar control and both aircraft visually flying in formation, United pilots are allowed to place the transponder in TA. This is to prevent nuisance RA's in short final.
Unfortunately, the Cathay crew could not fly or follow the ATC instructions. In this case, I would have abandoned the approach the minute I see the other aircraft uncomfortably coming too close to mine. Way before the Tower finally waves the errant pilot off.
SFO/NorCal controllers are among the best in the business, given the incredible task in hand. They also assume a pilot of a state of the art A-350 flying into the San Francisco International Airport can follow basic ATC instructions and possess basic flying skills!