Sure, but only because you asked. The magnet applies a force on the metal block, and the metal block an equal and opposite force on the magnet. The force is dissipated as a compressive force along the arm. All forces cancel out, so no net force is applied on the body.

Source: statics & dynamics 1

They are connected in the same system. What the truck is doing is the same thing as you holding two magnets together, you won't go anywhere because everything is self contained.

Edit: this is probably not a very accurate explanation but it's the way I understand it.

If the arm can bend, the car and the magnet could move towards each other until they come together, moving the car at max a few centimeters. If the arm doesn't bend, the car is pulled as much forward as the magnet, and therefore the arm and in turn the car itself, is pulled forward, leaving the whole system stationary.