To demosaic is to take input data from a color filter array, which specifies a red, a green, or a blue value at each pixel, and output an R,G,B triplet at each pixel. That is the definition you will see stated or implied on innumerable websites. As far as I know, there are only two CFAs in use in commercial still-photo cameras: Bayer and X-Trans. There might be varieties of Bayer arrays depending on how wide a spectrum of light they admit into the red, the green, and the blue pixel bins.
RT demosaics the DNGs in question. Furthermore, when it does, it reports X-Trans demosaicing. Therefore, Adobe DNG Converter does not demosaic the X-Trans CFA data in the RAF file. The program merely puts the data in a DNG package.
This conclusion is also consistent with the problem that has been diagnosed in the Guthub thread: Fuji changed some header fields in the RAF file with the X-Pro 2, but dcraw and hence RT are hard-coded to the format of earlier RAF files.