I wouldn't call the combo of black, blue, red and gold "girly" colors.
Maybe you could go more to the gold than bright yellow. Same for the blues and reds.
They don't have to scream PRIMARY colors.
I think your design idea is lovely and graphic and, most importantly, EXTREMELY relevant to the recipient.
eta: The quilt in the picture - those fabrics do sort of run "young" but that doesn't mean you can't use different fabrics/textures/etc. in the same colors to create a totally different look.