By brother's wife wants to raise his son "Gender Neutral"

She thinks it's best for the child to decide. She has purchased toys for both boys and girls and will let him choose what he wants to play with.

My brother's head is spinning but he doesn't know what to do. He works 14 hour shifts and doesn't deal with confrontation well from her. She has already threatened to leave him in the past. if the boy starts to play with dolls, she will identify him as a "girl" and will likely pursue hormone therapy.