Hi,
This could be the case in two scenarios, as the person you are talking to is a one man company who outsource works to freelancers or the other could be that he is the sales person as well as the developer.
Generally in any company the sales person do not play any major role in the production and the clients directly talk with the production heads or the project leaders. The sales person only come into role when the next invoice gets due or a routine check with the client to know if he is happy with what the production team is doing.
If this person is not making to talk to his developer so he might have the fear of losing a client, but checking his credibility is important for you, you can ask him to give you the contact details of his past clients so that you can know more about his worth and the quality he can deliver.
Cheers,
~Maneet