[notyograndma]

This is the CEO's responsibility, but if he won't make a decision, you need to be the CEO here. What's best for the company? Does having him as CTO increase or decrease the likelihood you get to the next milestone? Does it enhance or degrade the team narrative? This is important for raising money if you plan to or attracting new talent. (It would also mean you would need to fire him to hire a real CTO if that need arises). If him as CTO hurts the team, the decision is that he can't be CTO. But, you should dig into why he wants this beyond vanity, because there may be other ways of making him happy. (For instance, when two founders are deciding on who's the CEO, oftentimes the one who is not the COO will be made "President". It doesn't really matter, but it makes people feel better).