This seems like an interesting semantic distinction. Certainly it seems worthwhile to consider how much you could make if you took a standard salary, or otherwise got paid more for your time. On the other hand, "profit" literally means "revenue minus costs", and "ramen profitable" thus seems straightforward: "enough profit to keep the founders in ramen (and rent)". Opportunity costs don't actually represent costs in the "revenue minus costs" equation, even though they seem worth considering.