I just don't see this play as being any more or less taxing then the other 50 plays they run in a game.
Jason Kelce was getting flattened under however many bodies every time the tush push was run. Not hard to get the more impactful range of "
gotta play through it" injuries after plays such as that. Bruised sternum, torn rib cartilage, one or more cracked ribs, etc. I can imagine someone from the opposing team - even more than one someone -- pressing down into Kelce's torso with a knee or elbow as they remove themselves from the pile. Good place for a rabbit punch or similar if an opponent can (literally) swing it, too.