I have to agree. The experiment cited modified 30 articles with minor and cleverly-chosen falsehoods, and more than half were fixed within two months.
From that, Kohs then claims, "I think this has proved, beyond a reasonable doubt, that it's not fair to say Wikipedia is 'self-correcting.'"
Um, WTF? That statement proves he's not very good at making accurate statements. If he added a time period to that, and maybe some disclaimer about the popularity of articles being modified, then it wouldn't be much of a point, but it'd be closer to true.
Based on the experiment, it seems that, given enough time (ie. given sufficient time for users to review those items), it is fully self correcting.
IMO, the most important feature wikipedia has, beyond the raw data, is the history of edits. There were loads of mistakes in encyclopedias I used as a kid, and they continue to make updates to them year over year, but it's nigh impossible to check the history of a questionable or curious statement in one.
Adding to that, at any point when someone notices some falsehood that was added (and about 15 of the 30 tested were noticed), that editor could then search for all edits by that user, and check them or flag them. That may not happen every time, and some things may not be caught for a long time (especially made up articles about made up things that no one ever looks at), but it's ok... it's a living document.
Oh, and I have no problem with edits and contributions slowing down. That's good. That's usually a sign that something is approaching stability. We don't want violent amounts of change to factual reference material.