I would say it's the other way round if it does anything like that at all.
None abs bikes don't have a front sensor but all bikes have a rear sensor. Even on abs bikes with front sensor, if the rear one gets covered in metal paste from the rear bearing the speedo fails and errors come up on the dash.
When the rear sensor is disconnected the BRAKE FAILURE warning will flash alarmingly but all it does is disable the ABS. Brakes work fine. The speedo wont work for about 5 minutes, then the ECU will get fed up of trying to find the sensor and switch to the front sensor. The speedo needle will swing up as you ride along.