I say that simply because needing to be needed is directly out of the Enneagram, and while ISFJ and that type is very correlated, other types can do that.
However, I'm not sure what to make of it because Nienna claims to be a type 5, and that's about as far as you can get from being the type that needs to be needed. You did make a good point though, and I suspect figuring out her relationship with needing to be needed will help guide her to her type.