The conventional wisdom for most stab wounds is to leave the object in the wound until medical help can arrive. Removing the object can increase blood loss.
With an open wound, you’re told to put pressure on it.
And, if any spinal injuries are suspected, you’re told not to move the victim at all, for fear of making the injury worse
If the same facts hold true for victims of crushing trauma, keeping them pinned might very well keep their blood pressure at a healthy level and prevent spine-damaging movement. Freeing them could release the pressure on their wounds and cause the rate of blood loss to increase.
So I don’t know of any verifiable stories, but it sure seems plausible given what we know about injuries. (Now, we do have to maintain some skepticism about Hollywood portrayals. Every character in Hollywood lives long enough to deliver their last speech.)