^^ My dad had career ending/life threatening concussions at UNC. They told him one more head shot and he'd likely die on the field. Took away his scholarship and sent him packing. He's 63 now, was suicidal and depressed for a good 20 years, and forgets my name half the time I talk to him.
What we're talking about is a guy who didn't have that, he was concerned and decided to call it quits. There wasn't some traumatic nearly dying on the field hit. It's one step away from laughing at the Lions player who was paralyzed on the field years ago. Locketts injury was brutal and he can't even move his neck right.
The "joke" Chree pulled up wasn't even about dude specifically, it was about that god awful off season the niners had when like 6 guys retired!