Hi,

To add some concreteness to my suggestions I'm attaching to possible
patches.

The first introduces a global `org-confirm-babel-evaluate' variable
which defaults to t, meaning all code block evaluations will require
explicit confirmation from the user.

The second patch adds an `org-babel-disable:emacs-lisp' function which
can be called from a users configuration to ensure that *no* emacs-lisp
code blocks can be evaluated on the user's system.

Best -- Eric