What does "fidelity to the truth" mean in the context of ideology?

Think about a SF movie like Gravity, fidelity to truth is making sure the details are coherent with the way reality works, with the way we currently understand reality to work.

Science doesn't tell you what your values should be.

In a certain regard this is true. Science doesn't tell you if you should be a sociopath of a pro-social person. However, once the pro-social stance has been selected, science can point at what values have a track record of providing this pro-social outcome. Cooperation, compassion, forgiveness... this have documented outcomes. There are scientific studies regarding what is conducive to happiness and meaning. There is the whole field of eudaimonia studies that is clearly pointing towards specific values. It doesn't tell you how to prioritise them but it sure points at what they should be.

Greed, altho a value to some... is not something that has pro-social outcomes (not to my knowledge).