[CSS21] is 'all' the 'initial' value of @media ?

I've been reviewing CSS techniques for assistive conditional content, such
as the technique in the WCAG drafts:

http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS/#C7

I went to CSS 2.1 to confirm my understanding that

<rule
class="toConfirmOrDeny">

If no @media rule is present in the context of a style rule, the
effect of that style rule is the same as if there were an @media: all
rule in the context.  The subject style rule applies to
any media type.  (Properties assigned in this rule will apply or
not apply per the applicability stated in their defining paragraphs.)

</rule>

Somehow, the section on the @media rule fails to say this.
http://www.w3.org/TR/CSS21/media.html#at-media-rule

It is, however, stated with regard to the @import rule.
http://www.w3.org/TR/CSS21/cascade.html#at-import

1. Is my interpretation above the same as your reading of this specification?

2. Is this a bug in the specification that this is not stated in the 
@media section,
or does it follow from general language on selectors or the cascade somewhere
else?

Al