Like many issues flying jets this is left deliberately not addressed because airmanship should be applied using common sense as a back up to these automation systems.Personally I always place a hand back on the thrust levers (even on an airbus) once the gear is up because I was once taught a good lesson.Departing VTBU at night with a close in turn and the autothrottle in "throttle hold mode" ie thrust levers should not move before the selection of another vertical mode, the left thrust lever , at around 600 feet very rapidly retarded to idle position for no apparent reason (pre-fadec engine).Fortunately this was picked up in my scan and take off thrust was immediately restored but this could have ended quite badly.