On another (explicitly unnamed) mailing list, there is discussion of
replacing the standalone info reader w/ a specially-dumped (purpose
built) Emacs.  Reuben Thomas posted a workable sketch that exposes two
problems (i.e., "code enhancement opportunities" as was known in some
circles):

 - forced async operation of ‘man’
   workaround: zonk ‘start-process’

 - reliance on /bin/sh to display a message to stderr
   
The first can be addressed purely in Lisp, and is not the subject of
this message (i trust someone will DTRT).  The second is part of a more
general infelicity in using Emacs in batch (or "semi-batch") mode.  The
global var ‘noninteractive’ is much too crude a switch for such cases.
So, refinement is indicated.

But where?

At first, i tried mucking w/ src/print.c func ‘strout’, interpreting a
small-integer (file-descriptor-ish) ‘printcharfun’ as a specification
for stdout (1) or stderr (2) in another ‘else if’ clause.  This failed
to produce output, and i didn't investigate.  Was i too hasty?

The second approach is attached (caveat: just a sketch; no multibyte,
locale, bidi awareness; poor error handling) here: