Let’s replace a few categories of your argument and see how your logic holds up.
”This is not the claim. The claim is that, empirically, many (or enough) of the men who end up in construction jobs are underage, trafficked, or psychologically coerced (due to poverty, drug addiction, abuse, etc) such that the choice is not really the free choice of willing participant.
I am all for individual freedoms, but I've read enough about this issue, and seen enough documentaries, that I think the claim is very well-founded. Of course, some construction workers are just willing adults doing something they want to do, but there are many who are not.
You could replace construction with mining or fishing or factory work. It’s pretty clear to me that outlawing fishing jobs isn’t going to solve the problem of forced labor.