For a specific example, "the user might be making Friends-Only posts, or simply use the account for reading friends' posts and commenting on them," just seems a bit weak of an argument not to delete journals for inactivity, since anyone can easily check when a user last posted an entry (by checking the full userinfo page), or how many comments he has posted (again, by checking the full userinfo), or if any users list him as a friend (by doing a directory search). If I verify that none of the stated reasons could be the case (e.g., I come across a year-and-a-half-old journal with no entries, no comments, and no friends-of) - which is not difficult in the least - then these arguments are very weak.
Studies have shown that Americans, when presented a weak argument in favor of something, tend to come out against that something. In this case, presented with weak arguments against journal deletion, the average American will come out in favor of it.
Granted, the point of the FAQ isn't to convince the user of the sagacity of LiveJournal policy, but if it's going to give arguments, it might as well give sound ones:
(1) "Some users also find themselves without Internet access for prolonged periods of time, but will continue with their journal at a later date" (in the FAQ as it stands) seems a perfectly sound reason; and we could add, "even if not, they may wish to reread their old journal entries."
(2) "LiveJournal has officially stated that it would never delete accounts for inactivity. While, under the Terms of Service (http://www.livejournal.com/legal/tos.bml), no such statement is legally incumbent, it is considered unfair for LiveJournal to delete a user's account for inactivity, having guaranteed the user that it would not."
(3) "There have attempts to develop absolute, objective criteria given which a journal can be considered 'abandoned'; such attempts have never been successful, simply because of the wide diversity of legitimate uses for an account. In the absence of such criteria, there is no way to decide which journals can be deleted and which cannot, or which people deserve to keep their apparently-abandoned journals and which people do not."
Your opinions, please?
Bonus random fact: in the TOS appears the phrase "new pay features."