Digital BW, The Print

Question for users of the MIS Variable-Tone inksets and Paul Roark's
adjustment curves:

One of the steps outlined by Paul and others on this list is "convert the
image from grayscale to RGB."  Most of my work is restoration/copying of
older photos.  Although I am merely a neophyte, I have read several sources
to the effect that even though the original image may be B&W, I should SCAN
and then WORK within Photoshop in RGB.  Prior to printing, the image should
be turned into grayscale using the Photoshop Channel Mixer or selecting one
of the R, G, B Channels, but not directly converting to grayscale.  Among
the reasons this all-RGB workflow is espoused is that it potentially allows
for selection of the "cleanest" of the R, G, and B channels, finer
adjustments, better contrast and three dimensionality, etc.

If, in fact, working the B&W image in an RGB space allows for the aforesaid
benefits, then it seems to contradict the workflow of using MIS VT inks and
Paul Roark's curves because if one of the steps is "convert the image from
grayscale to RGB," then the image must have been in the grayscale workspace
and not RGB, or such conversion would not have been necessary.

Given the names of well-known, experienced users who contribute to this
list, not to mention Paul Roark himself, I must be missing something.  Would
one of the experienced MIS VT/Roark Curve users point out where in the
workflow I am missing the boat.

Thank you.

Howard