[Logician]

Frank the owner of the post that has been tagged with [news] tag must be recognized as a news poster in options of the hack. So you cant edit someone's post and insert news tag to drag that news into your main page (UNLESS that person is allowed to post news).

Unfortunately it cant be otherwise:The hack can not know who inserted the tags, you or the post owner so it just checks the post owner's news permission if it runs into a [news] tag in a post.

Possible solutions:
a) as you figured it out, you can grant all news posting rights (or disable to option to grant it to everybody). Of course this is not recommended but it is not so bad as it looks because most people wouldnt know how to post news even if they are granted this privilage in the options.
b) You can reply the thread yourself and use [summary] tag in this thread. So forum reader wouldnt know about the hidden news message in your post, but with summary tag you can drag any message text as you like to your main page. eg. you can put other users messages in between your summary tags.

In my board I personally prefer to use summary tags to make a thread news thread.

Hope this helps a bit..