the umbrella includes stuff like onlyfans and strippers, so there's not necessarily sex happening there to be rape.

if you want to focus on johns and prostitutes, i'd explore lines of reasoning like "the customer isn't the one doing the coercing and the pro-SW position includes being able to turn down clients" or "if you think capitalism coercing sex work is bad that should lower your evaluation of any 'regular' job that takes a physical and mental toll on the workers"