I'm curious as to why what you wrote above is true. Do you have any idea, or is that in itself a closely-held secret?
I don't know. I don't think it makes much sense, as recent bans are continuously published in
modlog anyway.
Unless this has changed, those bans are only from "autobans" that are done to newbie (?) accounts and temp bans will not be shown in hte mod log.
IIRC, the fact that someone is banned is not public because theymos doens't want people potentially trying to impersonate banned users to make it look like they are evading a ban.
Also, banned users can still log in (to my knowledge), and read the forum, but they cannot post.