Mature adults can certainly think that someone else is not fit for one job (running YC) and is fit for another (handling OAI). Good business people are even better at it, knowing that makes them more money. PG certainly seems to fit that.
Ycombinator still has a monetary interest in the for-profit corp of OpenAI right? When Sam says he doesn't have equity I believe he sometimes clarifies that he does a small interest through a ycombinator partnership or fund ownership of some shares.