Not letting unregistered users edit controversial
pages at all is
surely less intrusive than holding their edits for review?
Yes, because I think 99.9% of all unregistered user actions are reading, not
editing. Therefore we are dabbling with the unregistered user's Wikipedia
experience in a much larger way - not by holding their edits, but by not
showing the most current version (which, by the way, will in most cases not
even be an anonymous edit).
Ulrich