Given the manifold failure of a lot of Inhuman books, I don’t know how much of an audience there is for Inhumans stuff in general. But what there is boils down to a select few things, which I would emphasize: Kamala Khan, Lockjaw, and coming up third, the Inhuman royal family.
And to be honest, I only care about that last one because of Saladin Ahmed’s Black Bolt series. So my solution is: have him do the Inhuman royal family and he can figure out how to make people care.