You don't understand how salesmen work at all, and I'm not talking about them being shady, I'm just talking about general business practices.
Lists of names/numbers are for cold-calling, and yes, cold-calling should check any opt-outs first.
Once you are actually having conversations with a specific person about an actual sale, lists are no longer part of the equation. There's not a salesman in the world who, if asked by a customer to call them back (as happened in this case) would check a list before calling them back. It just wouldn't happen, ever. And frankly it shouldn't be expected to happen, the only time it would ever be useful to check a list is the very rare occurrence where the customer is trying to catch you out by telling you he's interested but he actually isn't.