It seems that there is no option to sort the news rss feed through publication date. However, this feature seems logical and we will add it in one of our future releases. So, thank you for pointing our attention to this issue. Your Telerik account has been updated.
The only modifications which are done for the RSS feeds information is by the dynamic link parser. Its function is to modify all relative link, which does not start with the protocol and domain used, to absolute one. Thus, if you have link similar to: /myApp/link.aspx it would be modified to http://www.domain.com/myApp/link.aspx.
The other thing which might be causing the problems of your client can be the item structure option in the feed settings. This is the option where you set what part of the content will be put into the feed - all of the article's content, its title and summary or its title only.
Please check if this might be causing the issues and let us know for any problems
the Telerik team