> Undoubtedly, launchd can be told to disable photolibraryd, but the approved mechanism wasn’t immediately obvious to me.
You want "launchctl unload /System/Library/LaunchAgents/com.apple.photolibraryd.plist".
You want "launchctl unload /System/Library/LaunchAgents/com.apple.photolibraryd.plist".
launchctl stop com.apple.photolibraryd
(And replace “stop” with “start” to get it going again.)