smallaxe, im not sure what your asking about the P not moving?
ground up powders/meals such as bone meal have more then just P, beside that once rained on it will move into the soil, i container grow/raised beds, i use these materials all the time, fantastic results if used wisely.
let me just talk about the rock P since it's a mine material and not of organic source. where the bone is more a food source compared to the rock meal,
faster break down plus the bone will contain N and other nutes and such
once the rock powder works into the soil and is Incorporated in the soil/OM the bugs will have a field day with it, major source of P Ca to draw from, once in biomass..the rest is obvious