That's up to Disney/Fox. If it was fully completed (or at least the majority of the work was done) and incorporated into the film before the studio got cold feet, then the studio owns the music and can do what they want with it. I suppose if Trent & Atticus were really happy with what they did and wanted to fight to release it in some form, they could go about doing so. It sounds to me like they're already moving on from it though.