That is understandable - I would be confused as well.
The Desktop-Packages changed 3 month ago when midori was dropped to AUR.
I believe it is an oversight - the firefox entry was not changed at the same time
The package listing is what you can expect for the installed system - they are informative but not conclusive.
The package listing does not include the content of Packages-Mhwd either - so if you grep the full iso list for an office suite or Nvidia driver, there is none. The packages installed as part of the hardware detection process and the user selection an office suite will not appear on any list unless of course you generate one by yourself - but who does that ?
There will be packages for tools used on the live media which is not installed to the final system e.g. Calamares and the iso grub theme.
It does not make sense to include those in the package listing - this would only create more confusion.