It applies to ALL aircraft. Show me in the AC where it says "manned aircraft" only or an exemption for "unmanned aircraft."
8. VOLUNTARY PRACTICES.
a. Avoidance of noise-sensitive areas, if practical, is preferable to overflight at relatively low altitudes.
b. Pilots operating noise producing aircraft (fixed-wing, rotary-wing and hot air balloons) over noise sensitive areas
should make every effort to fly not less than 2,000 feet above ground level (AGL), weather permitting. For the purpose of this AC, the ground level of noise-sensitive areas is defined to include the highest terrain within 2,000 feet AGL laterally of the route of flight, or the uppermost rim of a canyon or valley. The intent of the 2,000 feet AGL recommendation is to reduce potential interference with wildlife and complaints of noise disturbances caused by low flying aircraft over noise-sensitive areas.
You say that the above applies to UAVs. So the FAA is asking UAV's fliers to fly below 400' in order to be safe but here they are recommending that I fly _at least_ 2000' above noise sensitive areas. That might be a little difficult with any DJI product (read, impossible). Also, you really think the FAA is recommending UAV's fly at least 2000' to avoid excessive noise on the ground? The FAA is recommending that I fly my UAV at 2000' and higher.
c. Departure from or arrival to an airport, climb after take-off, and descent for landing should be made so as to avoid prolonged flight at low altitudes near noise-sensitive areas.
The FAA is stating when I take my UAV off from an airport.... wait.... the FAA expects me to be flying my UAV on an airport runway?
This advisory was issues in 2004. What drones were around in 2004 that the FAA needed to come up with recommendations for?
Do I think the FAA or even local law enforcement would look to cite a UAV flier for harassing wildlife (to include harassment by sound)? Yes. Do I think this advisory would be used? No. First, it's an advisory (recommendation) and two, I think it's obvious that it's not for UAVs. There are already national and local laws against harassing wildlife that can be used.
Edit: It does not need to specifically need to list what it does not apply to, it does not list paper airplanes either. Context rules out UAVs.