Limit user (not role) publication of content to specific menu subtree
Drupal's menu module is pretty good thing, but written with simple cases in mind.

Solution without using menu system:


Create a taxonomy tree representing the part of menu that gets repeated for each user
On node creation, omit menu altogether, let user choose taxonomy term from a tree instead
Use Views to render it all as one big tree, theming it so it would look like a menu


Added benefit is that you can easily move elements from user to user, allow users to change their names etc and it just works, no need to edit same thing in 2 places. And you can rename "menu element" once, in taxonomy, instead of "once per user".