Since none of these guys (the players, the coaches) are physicians, they should err on the side of caution. Even if the guy lies about the color of the sky or the time of day he can still suffer from concussion ~ particularly if he’s been previously injured.
The doctor saw NO reason to hospitalize James.
The doctor is already on record as saying nothing Leach did harmed or further jeopardized James's health to the slightest degree.