Why must music be translated literally?
Maybe a skater is using forebodingly dark music as the backdrop to tell a story of hope. Contrast.
First, I don't think I am saying it must be transcribed literally. What I am saying is most pieces of music can accommodate a wide range of interpretations and themes, but this range is not unlimited, and eventually when the point is reached where the music does not support the theme of the dance the PCs are going to take a hit. I can not accept your view that any piece of music can support any theme.
Second, should there be absolutely no sense of hope to be discerned in the music then I would say a dance purely of hope does not express the character of the music, and the theme of the dance would be better served by a piece of music that includes both foreboding (or the like) and an element of hope.
If a performer wanted to present a dance whose theme was not supported by the music, purely as a matter of unjudged self expression, I would say give it a go. But as a matter of scoring a competition, the performer is playing with fire.
In order to score the presentation of a program in competition, the PCs were set up with a specific set of criteria to be evaluated. The criteria are not necessarily the best list, or only list, that one could come up with. And the whole question of whether creating such a list is even a reasonable way to evaluate presentation is open to question.
But the list of criteria in the rules is the list we judge to. If the skater shows things on the list they get points. If they show things that aren't on the list they don't get points for those things. If they omit things on the list they miss out on points. This is no different from the technical side. Some things get points in IJS, some things don't. If you want to win, you put in the program the things that earn points.
If someone were to respond that this ties the hands of the choreographer, I would agree. But the choreographer is not creating an unfettered artistic work for the ages under IJS, they are creating a work that will earn points.