Concrete is underused in kitchens without a doubt. If only he was looking for a new kitchen work space and not a dining room table.
Thomas, two things come to mind. I'm having dinner at a friend's this weekend who had a beautiful table made out of a raw piece of walnut and bronze legs. Not exactly inexpensive, but I think you can do the look for less. I'd love to rip this idea off, but we're too close. Maybe keep your eye out for a great piece of used marble and go from there. I'll take a few pics when I'm there.
If you would consider rustic I am probably selling a 100-year-old round pedestal table from the Philippines. Seats eight. Maybe too rustic but it really does stand out and round tables are great for dinner conversation.