You don’t fail for surface rust, it’s not a check that’s done.
You fail for dangerous imbalance of braking force. When the car is run on the drum roller (rolling road powers the cars wheels) and the inspector presses the brakes, the braking force applied by the car is measured. You get a fail if your braking performance is likely to unsettle the car in high braking force scenarios.
Failing here is a real problem. It doesn’t warrant a dismissive surface rust claim.
Tesla does already periodically apply brakes even when regen would be enough to keep on top of surface rust. Tesla even applies brakes when excess water is detected:
“To ensure brakes remain responsive in cold and wet weather, Model 3 is equipped with brake disc wiping. When cold and wet weather is detected, this feature ...”
This has been a common feature on many brands for around 10 years at this point.
If a workshop has to do it the rust is quite bad and there are groves. Otherwise you can use the pads.
Unless your inspector has a particularly bad day, you will not fail the inspection for this. They might also simply ask you to do a five minute drive and brake hard a few times. If the brakes are still in a safe condition, this should be sufficient.
...really? One of the core elements of your car, the one that will kill you if it fails, is degraded, and that's not a big deal? What will it take?