I came to the comments to say much of exactly this. I think you worded it thoughtfully and were polite in your challenge to the author's viewpoint.
It felt like there was a fair bit of cliche in the article as well. It's not exactly a shocker to anyone who has tried sugar dating to hear the prostitution comparison, or have considered it themselves. The key distinction in my mind is the level of selectiveness. But then I don't really consider marrying for money substantially distinctive from either of the other two. And I have zero interest in sweeping moral judgments of any of these. Emotional connection was the other point I felt was stereotyped. I can't speak for everyone who has sugar dated, nor should I try, but I can assure you that emotional connections were front and center for me. But maybe I am an exception.
There is a question here that I feel might deserve exploration, and that the author alludes to: is there something inherently regressive and anti-feminist to the entire concept of sugar dating? I don't have an answer, but I think the opportunity for abuses due to the power imbalance is very real, very easy to stumble with, and is beyond the emotional maturity to withstand for many of the men who practice sugar dating (as shared to me by the women who have experienced these gents firsthand). @Hazlit has written some wonderful pieces on Medium exploring these topics in a sensitive way, I find. He also recommended a scholarly work: "The Purchase of Intimacy" is a book that explores the case history and inherent interplay in our culture between sex and money. It's heavy but very interesting.
Thanks to both author and responder! I love the engagement and discussion here.