Access instead of unset?

Might be less potentially problematic to use the #access setting of $form['menu'] ie ($form['menu']['#access'] = 0).
That way if there's realy is a menu it won't show the field, but the information will still be there for others to use (yeah, against the title, I just really hate the menu fieldset in the node).
I've tested it; doesn't even show for user 1 :).

I had a module figuring out the parent in a presave and this was causing duplicates to be made

cool module