Good discussion! One of the thorny questions on my boards was whether I would allow a teenager to checkout a book that details how to perform suicide. Strictly adhering to the code of ethics ("a librarian will allow unfettered, anonymous access to information"), I let him check it out without comment. As a human being, though, I would have a real hard spot not trying to also get him some suicide intervention numbers.
The problem with that, though, is that as a human who can't actually read minds, you don't know for sure the reason he wants the book. Perhaps he's simply doing research for a report. Suggesting and/or providing additional information is probably not a bad thing in most cases; but there are those who would go farther and simply restrict his ability to check out such a book.
With something like suicide, you'd most likely be in fairly safe territory simply providing info on prevention and counselling resources. But what about other, hot-button issues like sexuality, abortion, illicit drug use, "dangerous" material such as
The Anarchist's Cookbook (as you mentioned), and so on? It's a very tricky thing to anticipate the patron and offer what you would consider useful information, because of the potential backlash from the patrons, and especially parents of minors. Simply allowing a minor to check out such material has been the cause of some serious conflicts in various library systems around the US.
For a librarian to appear to "encourage" such things, or in a few cases, to "restrict" or "censor" them, could escalate repercussions. To do either, indicates that the library or librarian takes a more active role in directing the patron's access to information, and sets precendents that could be used as the beginning of a slippery slope. Give too much and you're seen as a promoter, withhold too much, and you're assumed to accept the role of "babysitter" and all the responsibilities and risks that entails. That was one of the resons that local libraries and librarians fought so hard against the Patriot Act's library patron records provisions.
To my mind, libraries exist to provide access to as much information as is humanly possible, regardless of the nature of that information (ruling out, of course, things like pornography or commercial promotions which are devoid of any real information). "Entertainment" media such as literature, cinema, music, etc. is just as important a part of that as informational media.
If a librarian is requested by a patron to assist in an information search, then I don't really see a problem taking a responsive role in providing assistance; but librarians should not be initiating assistance or assuming the direction a patron's search should go.
To use your example, you'd try and direct that young man to suicide-prevention resources. An understandable reaction, even with failing to determine the necessity of such a step in this particular cases (erring on the side of helpfulness is not generally a bad thing). But what resources do you direct the young man to? Strictly government-provided agencies? Religious organizations? Scientologist organizations? While I'm not saying you would, other librarians might.
How about a patron who is researching mental illness? Do you assume that they are looking for help with their own illness and direct them to... who? Local university health clinics? Hospitals? Controversial treatment centers? Anti-psychiatry Scientologist associations? Naturopaths? Again, while you seem to be a reasonable person, I've met more than my fair share of seriously woo-woo librarians (and recently had a falling out with one who, up until now, was a friend). A patron checks out books on illicit drug manufacture. I'm assuming no one here would call the police on them. But what about referring them to drug-abuse counselling? AA? Narconon? Abortion, do you refer them to Planned Parenthood or Project Rescue?
It's a very complex problem, and one I'm kind of glad I don't have to deal with. I'd probably end up like the OP, getting frustrated and handing in my resignation.