Sidepiece thinks prostitution should be legal

Or would it reduce it?
Legalized alcohol reduced illegal brewing and importing. 

No equivalence was suggested, other than in your own mind. 
The claim was that legalized prostitution would therefore legalize sex trafficking.
That claim was specious on its face, since forced sex trafficking would still be illegal and since adult individuals could engage in business openly.
Much like the repeal of prohibition.
That said, your attempt to make an equivalence between the two activities was either dishonest or very poorly thought out.   
There was zero indication in my post above - or in this one - that the two activities are equally desirable or equally objectionable. 
Happy to discuss the topic on its actual merits or lack thereof - but only if you are capable of refraining from misrepresentations.