When I first saw the title of this thread, I, too, was riled about it. But the explanation proffered sounds like a good reason to ban it. I suppose the posting of links to their sites could have been banned. But there are weak-willed (had to pause and think of a more pc way of saying weak-minded, but that too though) people who will be erroneously influenced to their detriment by such discussion as why it's ok for Catholics to join, etc. And CAF has an even broader cross-section than CathInfo to be exposed, many with modernist leanings already, who may then join, or go and run the idea by a modernist priest and then join.
My logic that Classiccom should have been banned was based primarily on who may unwittingly happen upon his posts and be swayed. This is consistent with why I would applaud CAF's efforts to limit Fɾҽҽmαsσɳɾყ discussion if their stated purpose is sincere. Whether they are sincere in their stated purpose is another matter about which I am not familiar with CAF enough to have an opinion.