Indeed, grain in color film is due to clouds of dye. And silver halide (silver bromide, chloride or iodide) is removed by fixer, but something stronger is needed for the silver metal. Color processes use bleaches or blixes to remove silver metal or at least convert silver to something that can be removed. A blix is a weak oxidant plus hypo to convert silver to a complex and remove it in one step. A bleach is a stronger oxidant that converts the silver to silver halide and then a separate fix step removes the silver halide.
PE