I'm not an expert, but isn't it more accurate to say that freenodes and other networks have "patched" the flaw via chanserv and nickserv bots to mitigate the problems with the network model? I know efnet doesn't want formalized chan/nick ownership, but they clearly dont like being the world's #1 ddos sink. Why not just include a master network quorum function and a grace period under which reattached networks don't get to merge their mode changes.
This is a deliberate choice by EFnet, it's part of it's culture and bravado.
You won't see this on Freenode.