No, that logic doesn't hold. Further, I think you're conflating two meanings of the word ideal. In the context of an ideal free market, the meaning is closer

No, that logic doesn't hold. Further, I think you're conflating two meanings of the word ideal. In the context of an ideal free market, the meaning is closer to hypothetical and is pretty far away from the sense of ethical or practical goodness. Also, it's not clear that an "ideal" free market is a stable equilibrium. And lastly, if an ideal free market permits the existence of corporations (I'm not sure that it does) then it must allow one to purchase another.