I haven't heard for certain what Travis Hunter's injury is at the time I am writing this. The review you shared is excellent. The doc pinpoints the dangers. I will add a little more about the spleen and liver being in danger with rib fractures.
The spleen and liver are highly vascular organs with a large blood supply. You can review the splenic artery going to the spleen and the common hepatic artery continuing to the liver as the proper hepatic artery in an anatomy textbook or internet page. The splenic and hepatic arteries also send branches to the stomach, pancreas and duodenum. The large portal vein draining veins from the small and large intestine drains into the liver.
Fractured ribs (and any fractured bone) can have cut edges that are as sharp as a knife. The ribs covering the spleen and liver can easily lacerate the spleen and liver causing a life threatening hemorrhage.

The doc also explains the danger to the thoracic organs and kidneys.