Not treating people as property is a distortion of the free market. If people aren't property, what incentive do companies have to invest in their education? Rich people would be much more likely to pay for the education of their slaves if they were assured of strong property rights over them. How can you properly price human capital if there isn't a free market in it?
Etc., etc. Free markets are amoral machines that discover price levels appropriate to supply and demand through transactions. They are not intrinsically good or bad; it is in the transactions that make them up that moral judgement comes in. But if the market is truly free, then there will be no limit on the kinds of transactions.
Well, you're not talking about capitalism. Your whole reasoning is based on a false premise, because there are limits to the kind of transactions allowed in a free market. In a free market, you are free to do whatever you want as long as it doesn't interfere with someone else's freedom. Your freedom ends where someone else's begins.
Hence, slavery not being compatible with capitalism is a fact, not a distortion of the free market nor a mere opinion.
We're talking about market freedom not individual freedom. You're confusing the two. Companies owned by larger companies can still both operate in a free market. It's no different in principle for people. And my irony was about phrasing the ownership of people issue in free market terms to show how it is distorting (and it straight out is), not to argue for it or that there aren't other approaches to the same problems.
Etc., etc. Free markets are amoral machines that discover price levels appropriate to supply and demand through transactions. They are not intrinsically good or bad; it is in the transactions that make them up that moral judgement comes in. But if the market is truly free, then there will be no limit on the kinds of transactions.