I see you've decided to change the sashing... I think that's a good idea for a more manly quilt. If your son doesn't want a quilt right now, I'd make it anyway and just keep it to give him at another time. Later he may ask you for one, or you could leave it to him in your will! It would still be his, even if it lived at your house for a while.
I love what you've done for your grandkids' quilts!