So as long as it's not off-road and it's properly charged, then electronic shifting is very, very reliable and standard kit for many ultra-distance riders, see, e.g. https://www.redbull.com/nz-en/trans-continental-race-kit-gui... and the late, great Mike Hall's bike https://road.cc/content/tech-news/219030-bike-check-mike-hal...
Benefits from an ultra-distance pov include quicker/cleaner shifting holds momentum better. Reduced chain rub and gear maintenance requirements. Less force is required to change gear which decreases the risk of repetitive strain injury. And the ability to add satellite shifters (aka "blips") to aero bars and the tops, which makes it easier to hold a riding position. Oh, and they can also be set up to be more intuitive to use than trying to remember how to juggle front and the rear mech's when completely and utterly spent :-)
All incremental at normal scale, but I can definitely see why it'd worth it to him at the scale of Lachlan's rides.
Surprising choice for a long race based on durability thats all. A guess it is a trade off decision -- work vs reliability.