You phrased this question way better than I could.
This person has a valid, subjective opinion on taking penis in return for cash, but it's not necessarily the case for everyone.
Note that I'm not saying that being a sex slave is better than working a low tier job. I'm comparing peeing in a bottle, having every movement tracked/optimized and skipping meals to deliver Amazon packages vs true freelance sex work.
How is that different from lifting boxes in some factory job, or whatever menial work?
I mean, I know the e.g. Christian answer.
What would the distinction be, however, without giving some special negative spiritual quality to having sex?