Can NRI(permanant) hold Ancestral Property in India

To my knowledge, there is no legal provision dientitling the NRI person from holding ancestral property in our country.

There is no legal infirmity in your NRI son holding ancestral property either singly or jointly along with cosharers.

It is his right to inherit the ancestral property as per provisions of succession law, hence there is no restriction even if he is a NRI/foreign citizen to hold such properties on his name.