Is your brother playing the X Box version with a controller as opposed to a joystick?
Is he playing arcade mode?
Is he playing instant action or Campaign.
If the answer to the Qs is yes to either first or second and Campaign, then I'm not surprised.
As has been said, this game can be run in real arcade , nothing-like-a-sim, mode.
But, using the mods, a proper joystick, a mouseview, etc as simmers do, then, apart from the drideckers being skittish, there is no problem.
It's only fair to the game/sim that anyone thinking of buying this should know of these differences.