Quite apart from all this, a "wall" comprised of steel palings could be easily bent out of shape by the simple expedient of using a steel cable lasso and then dragging a spike or two backwards with a decent truck. This would mean the wall requiring intensive patrolling and security checks, costing more than the wall in the first place.
The man is an utter idiot!
don't forget about the extensive tunnels already found and catapults too