The Texinfo manual is not registered into the Directory node during the texinfo package installation.

%post
if [ -f %{_infodir}/texinfo ]; then # --excludedocs?
    /sbin/install-info %{_infodir}/texinfo %{_infodir}/dir || :
fi

/usr/share/info/texinfo doesn't exist so install-info is not called.
Only /usr/share/info/texinfo.gz exists, so the test should read:

[ -f %{_infodir}/texinfo.gz ]

The %preun section and the subpackages are also affected.

Version-Release number of selected component (if applicable):
F-13, Rawhide (only checked the spec file here)