Wings are designed to withstand forces in the vertical plane, ie. positive and negative g's, not forces in the horizontal plane. By hitting the tip of the wing, maximum leverage would have also been exerted on the wing.
If it was me, I don't think I would have been too happy to take the a/c back to base, unless a proper assessment was done. How does assess if there was any damage to the root of the aircraft, unless panels are removed and X-rays conducted. Somehow I doubt all this would have been done. Knocking over a truck like that, would have put quite a lot of stress on the wing.
What do the mechanical engineer boffs think?