I wasn't the moderator who removed your thread but there is a little part in the rules that says something about:
1. Keep anything off the board that would get it shut down (read this is porn, illegal activities, etc).
The Nissan Manual is "proprietary material" owned by Nissan and cannot be reproduced and distributed without their permission, in fact, they charge a lot for a printed one and will allow a download for $20. I have no idea whether or not the site you linked to had Nissan's permission, but if they don't and our site allows the link, TitanTalk could be found liable.
I have asked the other moderators about the removal of your thread and hopefully the one who did remove it will contact you and explain why the thread was removed if my explanation is not sufficiently clear for you.