Actually, I think they take the ACT twice while there and the SAT three times. My recollection is that they do not have ACT/SAT prep per se, they take math, English, chem, physics, current events and vocab. I think the vocab in particular is helpful with both tests but I wouldn't say its ACT/SAT prep as one might have at a Huntington or tutor type place where you have specific prep based on sample tests, tricks of the test, etc.
The other thing to consider is that the time there also offers time to discern if this is what they really want. Even as a falcon scholar, they could change their mind. An improved ACT/SAT score will certainly improve their standing with the academy, but in the case they change their mind, the improved test scores will be advantageous just about anywhere else in terms of scholarships, etc.
My DS improved his ACT while there and that reduced our tuition paid at the college he is at for this second semester quite a bit.