If you google, rear brake fail, in Ducati…KTM…BMW GS….you will see that the problem is similar and repetitiveThere's a difference between a warranty claim/defective product claim and a product safety issue.
Trying to prove a product is defective does open up all those counterclaims from a manufacturer that you neglected maintenance, or the product was used improperly outside its original intent.
If someone actually loses their brakes because an ABS module fails, then that's a whole different issue. A braking system still has to be able to function even if the ABS module fails. Under 49 CFR Section 571.135- Standard No 135; Light Vehicle Brake Systems, under S7.8.3, it says that for service brakes on a vehicle equipped with one or more antilock systems, in the event of any single functional failure in any such system, the service brake system shall continue to operate and shall stop the vehicle as specified in S7.8.3(a) or S7.8.3(b).
So if your actual braking system has failed because an ABS module failed, that's a violation of the consolidated federal standards for ABS, and is most definitely an issue that should be reported to the NHTSA. Under that CFR statute, it doesn't matter if you never changed your brake fluid, brake hoses, of let the module sit in swamp water for a year; the brake system has to remain functional in the event of an ABS module failure. It's a product safety issue. A complaint to the NHTSA isn't about "Yamaha/Bosch makes a crappy ABS unit and I want a refund" , it's about "Yamaha's braking system as designed doesn't comply with the federal regulations regarding antilock equipped braking systems".
If you can't get a functional brake in the rear after it's been properly bled, and the only way you can achieve a functional rear brake is to replace the ABS module, then this point needs to be driven home with the NHTSA. If you're being told by a Yamaha dealer or an independent mechanic that the only way to rectify the problem is to replace the ABS module, then that should be thoroughly documented in your complaint, with names, dates, times, written estimates, etc.
I don't really know how widespread this issue is, as far as defective modules go; forums are great for a lot of good things, but they're also great at confirmation bias. But even one failure of what is supposed to be a fail-safe system is too many.