I'm not sure why he's not allowed to take it because from a logical standpoint, a sword god that can cut anything and has already cleared the game, which means he's saved Hyrule repeatedly, would be a much better choice to deal with Ganondorf than Link beyond a flimsy "but it's his destiny" justification that might not actually exist. Bee's not evil, he's far, far less of a jackass than Ajax or Jack and wants to go fight the big evil of the world, something he's much more qualified to do. Shit if I were the Master Sword I'd be giving Link the pink slip or at least a "stay at home for X period of days" notification.