The market your talking about (software-mediated freelance development) only works if the participants trust each other. If Odesk allowed the Indian programmer to steal IP, that creates a precedent, our at least a perception, that theft is OK. This perception discourages western customers from using the system.

This shrinks the market, reducing demand for programmers in India. Now MANY Indian programmers can't find work, even ones who were honest and efficient.

I think this effect is very important to keep in mind if you're concerned about the morality of the situation. The thief is hurting his fellow Indian programmers just as much as his western customer.