The GPL license document "COPYING" is not DFSG-free

[Number Six <40311.nospam@comcast.net>]

What's the dispensation on this:

 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.
                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^

I thought the whole hoopla over GFDL was invariant sections.
The entire GPL license is non-modifiable.

(1) Doesn't this mean that the GPL is not DFSG-free?

(2) Aren't slightly-different wordings of the GPL to produce 
slightly-different licenses derivative works of the GPL [they certainly 
are in spirit] and thus covered by the GPL?