This is a bit out of date, or just uninformed. MD5 is questionable, these days (the currently existing attacks on it aren't serious for most applications, but the door is open for more), and MD4 is known to be absolutely hopeless, and collisions can be found with very little in the way of computational effort. The upshot of which is that it would be theoretically pretty easy for a rogue node to cause undetectable corruption to files on ed2k.
Actually, i believe that is exactly what the article says: MD4 is broken, MD5 ius on its way ;) But if you consider it missleading feel free to fix it in some way. For the moment, MD5 can't be broken in the wayed2k uses it and, what's more, ed2k also uses SHA-1 hashes for AICH which is far from being broken at the moment. Now, I can't wait to see how you'd arrange the article to reflect current crypto status, so feel free to do so.