But I think (and please comment if you disagree) that:
(1) Some people might prefer the option to set a default security setting in their client (because it's easier to remember how to undo, and because it can easily be undone for a single entry), and if such a person posts a support request, it seems better to link to the FAQ than to give a whole explanation of something undocumented (though the clients will someday be documented on their own, hopefully).
(2) It might be worth noting that, even if you have set a minimum security level, you can still go back and edit a post to make it public if you like (because the option inserts the security level into the post protocol only, not into the edit protocol).
(3) Since the FAQ is now much more than just a "no" with explanation, that the explanation of how to edit entries should be dropped, because it prolongs the "no" and makes it unlikely that people will read past it; I think it should be replaced with a link to FAQ #2.
If you have an opinion, let me know; if people agree with one or another point, I can write up text for it.