There may be a slightly different explanation(s).

India and Pakistan acquired the weapons out of necessity and not because they are peculiar people. Generally the international state system will tend to support balance of power that is likely to maintain a preferred status quo.

There was a project in the US for establishing how quickly a country with fairly educated people can come up with the bomb and it turned out that it's not so difficult for a country to develop nukes. This could have informed the non nuclear proliferation treaty.

But with this treaty came a need for some countries to be given free reign otherwise the international system would have been unstable.

S. Africa surrendered its nuclear capacity for similar reasons, and generally countries will support the non proliferation treaty because in their contexts nukes would bring more disadvantage than advantage.

The idea seems to have worked given that both India and Pakistan have deescalated the conflict and localized the conflict to Kashmir.

BTW, there was a time, maybe last year when both armies engaged in non lethal warfare of pushing each other without extending hands, no punching no weapons.