I would expect that auto throttle (or not) to be aircraft type dependent. Manual thrust can destabilise the pitch/glidepath accuracy depending on engine location and autopilot speed control system (airspeed / alpha). In this case any dispensation would have to show that the (manual) system still met the approach accuracy requirements.
However, I note that JAR-AWO 321 (b) for operations down to 50ft DH, only requires that workload be considered.
For DHs below 50ft or no DH, then autothrottle is required, i.e. no dispensation. (JAR-AWO 321 (c) & (d))