A delightful sticky issue.
Let's start by supposing this is the 1950s, you are in the automotive repair business, and your former customer is attempting to obtain his servicing record from you. And you store servicing tickets in boxes by year in numerical ticket order. To what extent should you work for free? On the other hand, if you have a client folder, you might want to provide copies so long as the client is willing to pay reproduction costs.
Now, back to the present. If the client were audited by the IRS who demanded the data, doubtful the former actuary would hold the data hostage. It's a small client and sounds like a small actuarial firm that may or may not been employed under an engagement agreement and even so, such agreement might not have covered data transfer in the event the working arrangement was terminated.
My own position is that I'll entertain discussion to provide gratis information that the client hadn't sent me and that I hadn't sent to the client. Thus, if the new actuary were arrogant and annoying, I would indicate that I have operated from census sheets the client has provided and the new actuary should obtain these from the client. If the new actuary wants me to save him time, too bad.
In my past life working for a major actuarial firm, I saw situations where big dollars were charged for data transference.
In you client's situation, I advise the client to pay the $1,500 but make sure you understand what information your getting and in what format. Else, the client cost may greatly exceed what you have presented as a $1,500 rip off. And you need the data now and not after some lengthy legal or ethics battle.
Keep in mind. This is not your dog. The client needs to decide how to proceed. You need the data one way or another and its the client's money.
Still, you hate to see people stepped on but bull your neck.
End of consulting sermon. I'll personally email you to instruct where to send my consulting fee. This was covered in my engagement agreement!!!