Your interpretation of CLHS is debatable.
CLHS never explicitly says under which conditions it is OK to print (QUOTE FOO) as 'FOO. Likewise for backquote, for which clisp
has an elaborate algorithm.
Therefore IMO it's an omission.

CLHS says "list notation is preferred over dot notation". It does not say "list notation is preferred over quote and backquote notation".

The description of *print-readably* says that the "standard readtable" can be assumed when reading objects. Therefore you can
assume that the read-macro for #\' is in place, as much as you can assume that the read-macros for #\( and #\) are in place.

The rationale for clisp's behaviour is that the symbol QUOTE, when it occurs in lists, most often occurs when printing a piece of a
program. In this case, printing 'FOO instead of (QUOTE FOO) is always a win in legibility. Changing clisp to print (QUOTE FOO)
when *print-pretty* is false -- like SBCL does -- would be a regression, IMO.