It's not the same as a mailing list at all. It was person-to-person contact between David and yourself. Although it appears that the law was violated when you were called by David, he was simply following up on your interest in his company's products.
Honestly, I feel like you are totally abusing the law in this situation. At the first available opportunity, you should've asked to be placed on their DNC list without expressing false interest in their products. Then you would've been in the right by sueing for the first an all subsequent calls. It seems that you went about this in the most malicious way possible, even going so far as to essentially trick them into violating the law.
How do you suggest he find out who to sue without expressing interest in their product? It's really the company who is abusing the law by not disclosing who they are to avoid retaliation.
That's the thing -- the telemarketing company knew perfectly well they were breaking the law, and thus took pains to hide their own identifying info even when the person did seem interested.
Sure, the fact that the bad guys are "playing dirty" doesn't mean it's moral for the good guys to do the same.
But in this case, simply lying that "that sounds interesting" before telling them he wasn't interested any more doesn't seem too serious. It's certainly not illegal.
Honestly, I feel like you are totally abusing the law in this situation. At the first available opportunity, you should've asked to be placed on their DNC list without expressing false interest in their products. Then you would've been in the right by sueing for the first an all subsequent calls. It seems that you went about this in the most malicious way possible, even going so far as to essentially trick them into violating the law.