[azhu]

There is a lot that could be considered wrong about this situation and a lot of directions fingers could be pointed.

Dave should not have been of such importance to the company in the first place. When you hire a person who brings in domain knowledge but doesn't spread it around, you're more renting value from them than you are buying it. In scenarios when such a singular repository of vital domain knowledge is unavoidable, relationships between that person and the rest of the company must be overseen to ensure minimal adversity and maximal alliance.

At the end of the day, when you build a company you are building a team. The more each member is motivated towards the team's collective goal, the more you will be able to leverage the skills you hired onto the team towards the ends you hired them for. People like to think about technical skills as if they somehow exist independent of the human they are inside of. The reality is that the human is the portal through which the skill is delivered, and their human traits are of first class importance when considering how well they will be able to apply their skills should you choose them for your team.