When all locations are in front of a single display, in some situation within a multipoint conference the user wanna to have a really "mixed experience" also when content is shown.
In a UVC multipoint hosted H.239 / BFCP conference it is not possible to arrange the layout in this way that content is the biggest screen and all participants are at the bottom stripe.
In a endpoint hosted mutlipoint conference this is possible because the mcu is on the host themself.
The solution could be that H.239 / BFCP content will be handled by the UVC multipoint as a standard video stream if the user want to. ;-)