Failed PIP application for Autism/ADHD/Dyslexia

My son aged 47 is autistic (Aspergers), ADHD and Dyslexic. Recently he applied for Pips but has been turned down, scoring only 2 points for Dyslexia. The Tribunal has also agreed with DWP and refused his appeal, again only scoring 2 points.
Andrew had a very traumatic time during his education, he was severely bullied and was seeing the school psychiatrist and psychologist by the age of 9 because of his disruptive and bizarre behaviour. For the last year of junior school and the five years at secondary school, he was transferred out of area to schools that had a more understanding approach towards children like Andrew. For six years he was provided with a taxi at the County Council’s expense as he could not cope with public transport. The bullying continued throughout the sixth form, and University to a less extent. It took twice as long to gain his 2:1 (Hons) degree (six years).
DWP have said that: because Andrew had a late diagnosis; a supposed ‘normal’ education, reaching degree level; can drive a car and use a sat-nav; doesn’t take the maximum dose of his medications; has never attended a ‘memory clinic’ - he doesn’t have any of the problems outlined in his PIP application. Extensive information was provided in seven of the descriptors as to the problems Andrew has trying to live a normal life. We did a lot of research and hopefully used the correct terminology. He still lives at home and lives a narrow and restricted life.
Reports of diagnosis were provided from three different Consultant Psychiatrists and one Chartered Educational Psychologist.
With all of the evidence supplied, Is it normal for DWP to only award 2 points across the whole of the descriptors and have they simply viewed his application with disbelief?