I guarantee IB would take him as non-pro so long as he is not Selling securitized investment products.
If the OP is himself an insurance agent selling property/casualty and fixed life and annuity products, then he is not, per FINRA, and investment advisor, no matter what he thinks of himself, i.e. even if he thinks he is a financial advisor, he is not per FINRA regs. In fact, in the US he would be explicitly prohibited from marketing himself as a financial consultant, advisor, etc.
If, on the other hand, he is selling variable life and annuity products, mutual funds, or any other securitized product, then he is a financial professional per FINRA.
And even if he is a pro per FINRA, AMP should have allowed him to open the account with the professional designation and paying the professional market data fees, etc.
Unless AMP is notable to handle such pro business. Then there answer to him should have been AMP does not do business with people whom FINRA would designate as a market professional.
If you, or
@AMP_Global really wishes to figure this out, read an attempt to understand IB's guidelines on this issue. I suspect AMP could not produce such a document, and instead relies upon some employee's "feelings."
Guidelines on Market Data Subscriber Classifications | IB Knowledge Base (ibkr.info)