Individual desire remains therefore the ontological (existence or reality) root of all value:
Therefore, to say that compassion is a moral value is to say that when you are reasoning logically and understand all the relevant facts, then you will assign compassion a supreme value.
And there may be other moral values that supersede each other in hierarchies of supremacy, such as perhaps reasonableness over compassion: e.g. in any conflict between reasonable compassion and unreasonable compassion, you might conclude the former would supersede the other, or the latter would supersede the former
Whatever ones choice if on full and sound reflection, you have to decide between them, you want the one more than you want the other, and this would then be the true order of moral values.