I would imagine the sporting body would be concerned that any crowd member with a flipper zero could remotely shift gears on a racer's bike and possibly render it immobile.

Sounds like it is in the rider's own interest to not have a wireless bike.

Di2 is also commonly used in consumer grade electric cargo bicycles, used by a lot of people every day to take their kids to school and back. You don't want your gears to fail while doing that.

These have been in flagship consumer models for years now, and gradually drifting down into more mid-high level road bikes. Still talking about the $2k+ range but totally normal in the kind of bike your dentist or, frankly on HN, your coworkers, ride.