wetpaints
There is no reason why you should not pursue this with your MP, however, it may be of limited value as MPs are becoming more hesitant to interfere with this system, and the DWP are becoming more imune to their interfering.
Unfortunately there is no way to exempt your son from the re-assessment process, as unlike IB, there is no such mechanism.
You should be able to use the Tribunal decision as evidence to support his claim, despite what you have been told by the DWP, so hopefully it will be easier this time around, and maybe you'll get a more sensible re-assessment date.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
