I don't think so. People 'here' (on html-wg) have been talking about
using ISO-2022 as the character encoding scheme, not the document
character set. In fact, the observation was that it was perfectly
reasonable to use ISO-2022 as the character encoding scheme even while
ISO-10646 was the document character set.
To answer your finaly question, then, "the idea that character sets
based on ISO 2022 can be used as document character sets" is simply
wrong.