According to http://stackoverflow.com/faq#reputation, the edit reputation cap is 1000:
 > The other way to gain reputation is by suggesting edits to existing posts as a new registered user. Each edit will be peer reviewed, and if it is accepted, you will earn **+2** reputation. You can only earn a maximum of **+1000** total reputation through suggested edits, however.

And he won't be able to do unreviewed edits - [that's 2K rep](http://meta.askubuntu.com/faq#reputation):

> 1000	 Show total up and down vote counts  
2000	 Edit other people’s posts

So, I don't really think we should be worried. He won't be able to make unreviewed edits without asking / answering some more questions, as editing will put him ~940 below the unreviewed edit rep number.

**EDIT**, 7 Mar 2014: Just shy of a year later, the [user in question](https://askubuntu.com/users/147044/radu-rdeanu) has 31K reputation with almost 1000 answers. Sounds like a productive member of the community to me!