Neither Hertz nor Chase cares about whether you are renting for "business purposes" until a claim arises. That is when Chase will look carefully and require proof of the business purpose for the rental. If the rental is not for a business purpose, Chase will simply deny the claim and you will be on the hook for the entire amount.

This is no different than fraudulent bookings which include all kinds of other goodies. Nothing to care about until something happens. But, if you used a fraudulent code to rent at a discount, the contract and associated coverages are voided.