A female population of 52.5% explains the effect for dating, but not for founding companies. The difference is because it's the surplus that matters for dating but the entire population for founding.

Suppose that 42.5% of the population are women in a marriage or committed relationship, and then by definition 42.5% are also committed men. That leaves 10% of the population as single females and 5% as single males, and there's your 2:1 ratio for dating, created by just the small female surplus.

Would that hold for founding companies? I don't think so. Any of the 52.5% females could start a business, as could any of the 47.5% males. The small excess of women doesn't create a 2:1 ratio here. (There may be some correlation, that married and settled women are less likely to start a business, but the population ratio can't explain the entire outcome.)