Can he optimize his health better and track every minuscule macro and micro down to the mg? Absolutely, but what he’s doing isn’t necessarily unhealthy and it might be something he personally prefers. You have to have a balance otherwise you risk diving off the deep end and developing orthorexia
It can put strain on the kidneys when you’re about 3.5g per kg of bodyweight. For your brother that’s 215g so he’s close. You say he’s an athlete however and I bet the reason he’s been able to sustain it healthily is that he’s drinking a lot of fluids which helps the kidneys clear waste product more efficiently. I would be more worried about the fact that a higher protein intake would mean he’s possibly skimping out on a proper amount of fats and carbs which are both essential for body function