I'm not the hubby, but I have DH, 5 DS, 1 SIL, 2 DGS, 3 BIL and a FIL, so have done quilts and other crafts for guys of all ages. As long as the flowers are not prominant and don't look 'frilly' or 'girly' they usually don't even notice that hey there's flowers in that square there. The colors and the design of the blocks/quilt are what they notice first.
I did a mock camo quilt for a very 'gotta prove I'm macho' little 9/10 yo boy who thought he was big stuff and 3 or 4 of the fabrics had flowers and if he didn't get upset I don't think very many of the guys will. I told the little boy's mom that if she needed to, she could tell him the outline print flowers weren't flowers, they were amoebas!