I'm surprised it didn't suggest using red LEDs without phosphorescence, which has several advantages:

1. Red light preserves your dark adaptation

2. It doesn't have as much of an impact on your circadian rythm

3. Not using phosphorescence can increase the lifetime of the light, since you don't have to worry about the coating degrading

4. Red light is less energetic, so could potentially use less power.

5. Since an LED without phosphorescence is a single wavelength, telescopes (and binoculars) can use a narrow band filter to filter out the light pollution, without blocking most of the light from celestial objects.