But you *want* a sunset *not* to look neutral, don't you? I prefer mine orange or whatever, not grey. The whole purpose of manual white balance is to accurately *remove* any color cast, yet a sunset is *supposed* to have a color cast.
At different times of day, the color of light from the sun changes. White balance can help keep the light white, compensating for these differences. You don't always want to compensate though. Blue snow in the shade that I mentioned earlier is a problem. An orange sunset isn't.