I agree with the above, that you should not name the person.
As for extra time, in an academic setting, to get this - he 'should' have been tested, either with a full dyslexic test, or a cut down school one..
If he passed these tests, to get extra time.. then there is little you can do to disprove it, as no matter how many times you go to the school saying 'he isnt dyslexic!!!' you have no proof - yet they+he, have a test to show that he is.