Okay, this one is probably not an example I would have chosen to discuss logical fallacies, the quote in the original post, I mean. But then I'm just a doormat, so it's a moot point.
Anyway, they use an illustration about a physical disease, then relate it incongruously to 'apostates' who are said to be mentally diseased. False analogy, then, as a mental disease is not contagious in the same manner as a physical disease, at least not in the context of this discussion. Unless we're talking a sort of spiritual mad cow disease? I don't know. I guess you could argue that apostates are "mentally diseased" in the sense that they have an 'unhealthy fixation' on things like facts and truth. I generally like to know if Watchtower writers are maybe not being honest about the organization's history, teaching things that aren't Biblically supported, reading and quoting from apostate literature, sending people to their deaths. You know. So if that's my disease, don't cure me by any means.
The "disloyal teachings" of apostates should be easily dispatched with the "sword of the spirit", the Bible. Presumably, true Christians should have the cure to any such 'mental disease' that someone would threaten to spread if they really understand the Bible. Except that the Society is probably putting itself in the position of doctor here and insisting that its patients remain (1) ignorant of basic medicine and (2) dependent on the so-called doctor's expertise. No diplomas offered as credentials save invisible ones. And most definitely, never, ever, EVER try to get a second opinion.
Note that the Society refers to these "teachings" as disloyal. In the earlier paragraphs I'm sure they made their share of statements that such teachings are false, but using the word disloyal here brings a question to mind. Disloyal to who? To the writers of this article, of course! Because loyalty to them and loyalty to God are seen as one and the same.
Suppose a doctor told you that people you might come in contact with have a contagious disease. But he tells you also to never talk to anyone but him about this disease, never to get a second opinion from any other doctor, and never to read any books other than the ones he gives you about the disease. Also, he rarely if ever gives you any serious details about the nature of this disease other than that it's really bad and you should avoid it. And if you ask him too many serious questions about it, he then tells you you're infected with the disease and has you quarantined! That would be a more accurate analogy to use, would it not?
--sd-7