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:
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 has 31K reputation with almost 1000 answers. Sounds like a productive member of the community to me!
