I'd start by exploring what his expectations are-- you might find that he doesn't see much of a role for himself. I believe it is better to be a single founder when you are at the idea generation and prototyping stage, particularly when you are working on a small business. Working alone helps you stay focused and ship without any distractions from co-founder drama. Once you have something that feels promising, then go look for a co-founder.
If your acquaintance is OK taking a back seat for the first iteration, then I think your problem is solved. If not, then you should have a frank discussion about what each of you will bring to the table. Even small businesses are a ton of work. At a minimum, you could offload the less technical work so that you can stay focused. Perhaps he focuses on connecting with the customer while you build the prototype? Most founders underestimate the value of connecting with the customer in the early days and in turn don't allocate enough of their time/energy to this task.
I didn't consider that he may not see a role for himself at the beginning (or even at all). He has already spoken to a couple potential customers to varying degrees of interest, ranging from "show me a working version" to "take my money now."
If your acquaintance is OK taking a back seat for the first iteration, then I think your problem is solved. If not, then you should have a frank discussion about what each of you will bring to the table. Even small businesses are a ton of work. At a minimum, you could offload the less technical work so that you can stay focused. Perhaps he focuses on connecting with the customer while you build the prototype? Most founders underestimate the value of connecting with the customer in the early days and in turn don't allocate enough of their time/energy to this task.