they don't want to admit anyone who a.) cannot meet the technical requirements for the practice of medicine or b.) have a condition that could potentially interfere with you obtaining medical licensure.
It's the same argument that they use for not admitting that 4.0 chemical and biological engineering/nuclear physics double major with 26 publications in Science and Cell who scored a 14 on the MCAT due to his 'difficulty with standardized tests.' He may truly have a test taking disability and may truly be brilliant beyond belief, and might even be the best potential doctor since Osler. But if you can't pass the USMLE, you ain't gonna be a doctor, and it would be unfair for a school to take your $100k knowing you weren't going to be able to get licensed.