Looking at llDerezObject(), I realized it comes with a built-in protection against deleting no-copy items. I submit that llDie() should get the same treatment. Under no circumstances, ever, should a script in a linkset be allowed to perma-delete a no-copy item! Especially since llDie() doesn't return your object to Inventory, or Trash even (Sic!). Inside a script of my own, I can guard against it with 'if ((llGetObjectPermMask (MASK_OWNER) & PERM_COPY) == PERM_COPY) {' or something, prior to the llDie () command, but it only takes 1 foreign script inside the linkset to make for a massive griefing tool!
Therefore, llDie() should fail silently when the containing object is not copyable by its owner, matching the protection already applied by llDerezObject().