If you reduce demand for nuts, their availability declines and you unnecessarily put the lives of hundreds of thousands of such people at risk.
This sounds pretty farfetched to me - possibly My nephew supposedly has "Celiac disease" and a bunch of other things wrong with him too and he eats rice, beans etc. Possibly starving because of lack of nuts vs death in a couple of minutes due to anaphalactic shock seem like no contest, besides they can always eat nuts at home.