First let me thank all of you who lent your kind words and support. It was very helpful, especially in the day that followed the accident. As mentioned in the OP, the good news is that he is not seriously injured. He suffered, as one might imagine, major bruises to shoulder, ribs, hip, leg and ankle, all on the left side. His "road rash" is primarily on his shoulder and hip, but he did lose a good bit of flesh. All in all he got off very lucky with this one. His bike frame, a Giant ORC1, is completely destroyed. Amazing to me, however, is that all of the parts are OK. The frame was pretty much folded where the impact occurred, but other than scratches the rest of the stuff could be shifted to another frame.
Now the frustrating part. It appears he was riding a new road for the first time, came upon an intersection and blew through a stop sign that he didn't see. Being highly skeptical about his not seeing it, I went to the scene of the accident, and unless you were a regular user of this road, there's a more than reasonable chance you wouldn't see the stop sign either. It was covered by overgrown branches from trees and bushes. You had to be almost parallel to it to know it was there. My sense was that unless you were walking, you'd be moving too fast to see the sign until it was too late. This was confirmed by two neighbors we spoke with who said that there were quite a few accidents at this intersection. Additionally, I checked the path the pick-up truck had to be traveling and found that the truck had to come up a slight rise and curve, making the intersection almost invisible until about 30 years away from it. This is likely why the truck was not moving more than 25 or 35 MPH. So, given these facts it's pretty hard for me to be too upset with the driver of the pick-up truck. Come to think of it, the accident pretty much must have ruined his day too.
Once again, thanks for all of the words of support. It's one of the things I like about the 50+ group.