The marketplace is not a moral absolute. Simply because an activity yields a financial profit, it does not mean that the activity is moral and ought to be permitted or protected. Opposing such an activity is not to oppose capitalism but to oppose some of the things capitalists (and others) sometimes do.
It is both legal and profitable to work as a doctor for Planned Parenthood, to sell medical marijuana in California, and to run a brothel in Nevada. One can make a handsome profit doing these and similar things. But that does not mean it is right or that those activities ought to be maintained and protected. It does not mean that such activities are above criticism or beyond approach. By criticizing or reproaching them, one is not opposing capitalism or the free market, as if market exchanges were to be free from criticism or opposition. The free market is not, nor should it be, absolutely free. It is free within limits. Its freedom is a matter of degrees, not an all-or-nothing false dilemma, as if you must have either all freedom or none. Other options present themselves. The proper debate is over the limits of economic freedom and where those limits ought to be placed, not over whether the market ought to be either completely free or completely coerced.
The voice of the market is important and deserves to be heard, but the voice of the market is not the voice of God. Some of the things it rewards or sustains are evil. Because they are, they will lead eventually not to human liberation but to human enslavement. Never forget that you are not free simply because you are doing what you choose, as if you could not be a slave to your own wicked, destructive and self-enslaving habits or addictions. Like all other things that humans are and do, market activity is fallen and bears the burdens and curse of sin. To keep the market as free as possible, you need to limit some activities within it, activities which, if let loose, eat up freedom and swallow it whole.
Or, to put the matter another way, those who decide which things ought to be permitted based upon their success or failure in the marketplace commit the old mistake of trying to move from “is” to “ought.” They move from descriptive statements to normative statements, or think they can. Simply because that’s how a thing is, it does not follow that that’s how it ought to be.