Thank you for the opportunity to help you with your question!
It is unethical to try to lure anyone into another company. In this case the contact was made to the CEO, but it would be unethical to lure any person from a company to another company. Ethics comes with the concepts of right or wrong behavior. To be ethical, one has to be for what is right, and to be unethical one is going towards wrong. It is wrong to lure or tempt someone to do anything that would take them away from their own career choice.
Please let me know if you need any clarification. I'm always happy to answer your questions.