Being an Airman, you should know about ejection seats. Military fighter pilots are trained in their use and they have saved many lives. When you eject, you are trained to keep your knees together and your elbows in. Songbird did not. 'Course, he would have failed flight school except for his Admiral papa. That may explain his injuries, but but I'd no excuse for the injuries he has inflicted on his family, fellow POWs, and our country since.
The missile that hit his plane caused injuries first. The ejection might have also, but it’s not like he ejected in training or whatever. His aircraft was toasted.
Being an airman, I knew that some people were killed or severly injured during “routine” ejections (well, nothing really routine there!). The canopy might have got in the way, as you say they might have not tucked in arms or legs, something on the flight suit or helmet/tubing/comm wires got hung up—even had a guy hit in the face with his map and clip board and broke his visor and ripped him up—a lot of $hit can happen.
Ever wonder how a wheat straw can get lodged into a telephone pole during a tornado?
Speed kills.