You have reached out to him for advice, then definitely start from there. Given his executive experience, he probably has the background and network to give you valuable feedback. You could focus your feedback gathering about your product, market fit, potential customers, pricing etc which will help your understand if he might be interested to try/buy it.

I would say you have nothing to loose and only to gain from the conversation. Maybe you may not be able to sell him today, but you walk away with advice and possible connections/referrals