A ruptured spleen causes internal bleeding. It's one of the more likely traumatic injuries to the abdomen. If you have had it removed, internal bleeding is less likely.

> If your spleen has ruptured, you may need a splenectomy immediately because of life-threatening internal bleeding. A rupture may be caused by a physical injury, such as being hit by a car, or by an enlargement of your spleen.

https://www.healthline.com/health/spleen-removal

The article mentions that if he had a spleen it would have ruptured from the fall and he would have bleed to death.

The proverbial spleen. Every "survivor" had this extraordinary luck that happened to position them just the right way to come out on top.