Neither of you has a clear picture. That is, he doesn't think of MVP in terms of programming and you don't in terms of the business domain. In other words, both of you may be right...and wrong...and talking past each other. That's the benefit and price of diversity.

To me, it comes down to has your cofounder been doing their job. Are there users lined up? If you shipped today, would someone other than the two of you and your families care?

Neither of you is an expert on your company. If your cofounder has users lined up, then they've been doing their job. and the tact with patents is to evaluate the degree of distraction their pursuit creates. And patents, despite the HN strategist, are not a bad tertiary exit option. The problem is they are slow and cost money.

Good luck.