Legally it is quite simply. The Intellectual Property is owned by the business. If you are self-employed the IP belongs to you. If you are employed the IP belongs to the boss. They created the environment making it possible to create the IP for.... them. I have had customers who wanted detailed drawings, source software etc. . There is no way they get it. A boss asks in principle for what is his. You should see their valuing of this situation by the end of the month on your bankaccount. The labour of training can be seen as a different type of employment, a trainer-trainee situation, which should put you in another scale. So story told, if you take the last choice as employee, they can call it obstruction.