Slightly controversial opinion here, but Katoa is partly responsible here
If you take a heavy hit to the head and don't tell someone you feel out of sorts, it makes the medical and coaching staff's jobs harder to do
Players are good about speaking up when they tweak their hammies. They also have a responsibility to ensure staff know what's going on upstairs
Obviously the medical and training staff have the main responsibility, and collectively here they've looked the other way - probably because he's one of Tonga's best players. But players too have an obligation here, especially when it isn't physically obvious