No one needs to sell it for that purpose. Application patents for non novel molecules can be gone around by a first year law school student. One simply sells the molecule without claims, or with other claims. If one wishes to buy it to use for the patented application he is free to do so. If it were a new molecule the patent would be valuable, and it would be much more difficult to circumvent it. This advice comes from a very good friend who is a partner in a patent and trademark law firm. It is pretty easy to verify however.