Nobody is requiring people to offer working unpaid Effectively you are. There are people willing to work for you or another startup and you tell them they can

Nobody is requiring people to offer working unpaid Effectively you are. There are people willing to work for you or another startup and you tell them they can only work for you for free. When you subsequently derive benefit from one of those people, they are effectively competing with payed labor, that would otherwise have been performed in the future, when you would have money available for it. You can twist and bend this all you want, but the outcome is that you are in fact breaking the law when you do such a thing. What you could use as a defensen is saying: "So what if it is against the law?". Law does not dictate morals. Laws often cover things they shouldn't reasonably be applied to. If you find it morally acceptable and think the net outcome for society is positive, then just do it. Defend it based on the intended outcome, instead of attempting a legal justification.