The problem with the safety cage concept is that there is little in the way of crush to extend the duration of the Delta-V. Even though the occupant(s) are spared from being pinned between the dashboard and the seat, the force due to rapid acceleration can be fatal by itself. At a certain point, aortas tear, spleens rupture, etc., so you're dead anyway. The deformation of the Jeep in this case was definitely good for the driver, as it stretched out the acceleration and more or less stopped at the firewall. The A-pillar could ideally have done a bit better, but we're asking a lot of a passenger vehicle vs. a semi.
As Rand said, this is 1000% a small overlap frontal crash. The rearward shift of the driver's door is a big telltale - along with other aspects of the damage to the involved vehicles.