All this talk about visuals/not visual, disconnecting autopilot etc. misses the point. The pilots missed the call to turn left hence the turn was delayed until ATC noticed they weren't turning and their radius of turn meant they would blow through the loc AP on or not. LOC can capture and still blow through the LOC. There are 2 relevant points. What distraction caused the missed radio call and why were they put into a situation that a single missed call could lead to such compromised safety. The latter we know is the nature of SFO ATC. The former none of us knows and we owe the benefit of the doubt to the crew involved because it absolutely could be any of us on a given day. Maybe cabin crew called just at the moment. Maybe they got an ECAM message. Maybe they were discussing where to have dinner. WTF knows. The system worked because there was altitude separation and CX followed the RA and it seems United perhaps did not but that's not 100% clear. Nothing to do with fear of disconnecting the autopilot or about hand flying at all. If they disconnected and turned a steep bank away from UA they certainly would have lost visual contact. So CTFO back seat drivers.