You can always get some benefit out of building links, but without content it can be an uphill battle. Will they do any on page optimization at all? If not, then this will be very difficult.
I hate to say this because it is not an SEO comment, but on the business side, some clients cost more than they bring in. It is up to you, but politely ending a relationship with an uncooperative client can be better than saying you can do it and not producing results.
