Support

It depends on your site. Let's see what the other core Joomla folders contain:

• cache This is temporary data which must not be web accessible. Therefore I would add a disallow rule in robots.txt about it.
• cli Scripts which must only be run through the command line (or a CRON job which is the same thing). Therefore I would add a disallow rule in robots.txt about it.
• components The private PHP files of components. It MAY also contain CSS and JS for some components. However, since there are no content documents there I'd also add a disallow rule in robots.txt about it UNLESS you WANT the static media files (CSS, JS, images, possibly some user-uploaded content) to be indexed by search engines.
• images These are all the images you have uploaded. I assume you want them indexed so do NOT create a robots.txt rule about this folder.
• includes, layouts, libraries Private Joomla! PHP files. MUST all be added in a disallow rule in robots.txt.
• language Private Joomla .ini translation files. MUST all be added in a disallow rule in robots.txt.
• media User-uploaded or generated content for etensions. MUST NOT be added in a disallow rule in robots.txt. It's the same logic as the images folder. There are some subtle differences between each folder but the bottom line is that you must not disallow them in robots.txt.
• modules, plugins, templates The same logic as the components folder. Disallow UNLESS you WANT the static media files of your modules, plugins and templates respectively to be indexed by Google.

As a rule of thumb I recommend disallowing indexing on all folders except images and media (the only directories which should contain user-generated content).

That said, I don't know the context of your support request to the RSSEO guys. Maybe they asked you to create this very basic robots.txt temporarily to troubleshoot something and then restore the file or add more stuff to it. So I won't tell you this is good or this is bad as I lack context. I'd say that the proposed very basic robots.txt is not good as a permanent solution but it's not going to cause you any problems as a short term troubleshooting solution.