It sounds like that hubber had major issues of some sort. Although annoying that you have to remove the broken links, I wouldn't take it personally: stuff happens. Perhaps that hubber was kicked off the site for some reason. Perhaps they got a new job or family member and are suddenly far too busy to participate in HubPages... It could be any reason.
I wrote an article for an organization that ended up closing up shop, and I had to go back and delete the links to it and unpublish that hub. They were a great non-profit, too, and I hated to do it, but what else could I have done? It wasn't my fault they closed their doors.