Overall good interview, however one ethical point. You can not assume your client's customers will come with you. In fact, it is unethical to solicit them. Remember the ethical hierarchy of obligations: General Public, profession, and employer. Your contacts can follow you when jumping ship, but you should not actively solicit them. I'm not NOT suggesting the young man did anything unethical. Just trying to illuminate the point not brought up on the interview.
Also the fact they may not follow you is a risk consideration you should address in your business plan.
@digitaldaemon74