A beautiful quilt, very chic and stylish. From his concern about "boy/girl things" I guess your grandson is more of a boy than a man yet, but surely he will be able to keep using this quilt well into his adulthood, in his own grown-up home.
There is something about "boy/girl toys" I read once, I guess it goes also for quilts and other things. "How to know if it is for boys or girls: does it have anything to do with genitals? If yes, it is not for children. If no, can be used by both boys and girls".