I don't think it is deterministic - and the things which make someone a good CxO are obviously (to me, at least) not something which you can teach easily, other

I don't think it is deterministic - and the things which make someone a good CxO are obviously (to me, at least) not something which you can teach easily, otherwise MBAs wouldn't have such a shoddy reputation. It is more of a fusion of age (which implies experience, even if not a linear relationship) and diversity within the experiences a person has had. It's a continuum. The OP stated some limited amount of experience in bizdev right out of college, which doesn't qualify you for the role of dog-catcher as far as I'm concerned. The startup experience itself is probably worth 2-3x the equivalent years in that bizdev role, but still I'd say they are on the low end of the spectrum for someone I'd trust being in charge of a company. If they had a couple more years of corporate experience or another startup on the resume, it would be a different matter.