I would go with the mother's wishes but I like the idea of a black, gray and white log cabin with the different colored centers. That would be cute! Also, keeping in mind that babies don't see color anyway many developmental baby's toys are black and white.
I honestly would not do double work by doing a double sided quilt. But I do think a bright backing would be fun and give a nod to the colored squares on the front. Then the mom gets what she wants and you get a nice color fix as well. Good luck and I hope you'll post a pic when you're done.
