I don't agree with his "of course I still own the source code" attitude. If he uses his own framework to create the application the customer wanted, he'll have

I don't agree with his "of course I still own the source code" attitude. If he uses his own framework to create the application the customer wanted, he'll have to explicitly tell them about that part. If it's an engine that presents courses in web-form, the engine is still his, but the content belong to the customer.