One thing we don't know is how the magic behind the smoking mirror happens.
Therefore we have no idea what kind of undertaking it would be.
What if every single 'marker' that BiaB uses behind the scenes is related to the bitrate used? (I wouldn't doubt it).
What if every single Realtrack would have to be manually re-marked for these positions to know what section to use when generating? That would be a lot of rework.

The point is, we don't know how much work it would be to add 24-bit. Or how much benefit we would gain at this point.
My hunch; the original studio recordings are probably higher quality than 16/44 but if it means going back to square one for every single realtrack .. well that's more costly than the GUI rebuild many have been hankerin' for.

I suspect that when a SEQ file in RB is set to 24/48, the program still uses the wma or 16/44 bitrate to generate any new parts, then upconverts afterwards before writing to disk.
That order may be telling us something.

Make your sound your own!
.. I do not work here, but the benefits are still awesome