More than agreeing or not with this line of thinking, I find the bigger problem is how selectively it is applied. People will point out that if we ban guns, we wouldn't have to worry about school shootings. Even if we ignored the logistics of such a challenge and agreed on the conclusion, why is the same logic not applied to things like alcohol and all the harms that results (drunk driving, alcoholics ruining their lives, etc). And some people do that (I think MADD would be one case, especially for the subset of their members wanting to ban all alcohol); yet even in that case those people selectively apply the same reasoning about something else.
Look at those who ignore the harm of buying drugs from unverified sources, where you may be paying money to a supply chain ran by the cartel. People are tortured and killed to get the drugs delivered, and if one doesn't verify (or if one insufficiently verifies) then they are funding such activities, but many are willing to ignore that. But change from drugs to escorting and you'll find some of the same people now saying that it should be banned because without sufficient verification it is possible to paying people who are coerced or forced into doing it. The overall argument has valid points and problem points, but the discrepancy of when it is applies makes discussing the validity harder when it seems people aren't being transparent about their motivations to begin with.