Overall, you're simply setting up a strawman that poorly characterizes your opponents. There are many reasons why someone would oppose sex work, including concern over the safety of the sex workers. Even if it were fully legalized and regulated there would still be significant risk when you have two people who don't know each other well in a room alone together and questions of sex and money are money are involved. Especially if it is a physically stronger man with a woman. The more cogent arguments take that into consideration along with the other effects such as sex workers becoming trapped in the occupation, the poor prospects for aging workers to earn an income or be able to retire, the second order effects on the community which are poorly understood but could be far reaching, economic effects of making the occupation more available to the working age population who might otherwise pursue other careers, etc. All of that generally lines up with the conservative take on any change which is to ask "Are you sure you have considered all of the consequences?" and "Do the benefits outweigh the costs both short term and long term?".