Of course, Kashus wouldn't just do things for allies.
Without sufficient benefits, alliances are meaningless.
This is true even for allies in the Kind Alignment... Without shared interests, helping each other is simply called making friends.
However, Kashus is the only one among the Four Elemental Gods who is very interested in the Prime Material Plane and even willing to respond to certain great ceremonies by his followers.
Therefore, he would certainly be interested in a world that has been disconnected from the Elemental Realm for many years.
He genuinely enjoys developing new territories.
Kashus has a mindset derived from the will of fire: perhaps it's to burn the whole world.
Just like that fire which, if possible, would never spare any space, burning freely... Its revival from the ashes further proves his nature.
