A 22 year-old is not a kid.
Don’t know how old you are; I’m 53. Assuming you’re probably within a years up or down of me.
A 22yr old isn’t on the same level of maturity, nor wisdom, nor knowledge that you and I are.
In her case, I’d say she was still a “kid” in way of thinking, and clearly in the immaturity of her choice.
But techically, yes, you’re correct. Maybe it would have been clearer saying that she still had a youngster’s brain.