I noticed when I read this on Slate a few days ago that LW doesn't say how "messing around online" led them to looking at "several" sugar baby websites.

I suppose "how can you think you have the high ground, she might be selling but you were trying to buy" wouldn't work for trying to talk LW into apologizing and not harassing their sister. With or without the quotes around "friends," LW told their sister "it would kill our parents to know you were doing this, so stop, and now that I've gotten the scolding out of my system, please hook me up with someone who's doing what I told you not to, because it absolutely won't upset our parents if I buy what you shouldn't be selling."

Like likeaduck, I read LW as a would-be buyer of sex, not a seller. (If the LW was a woman who wanted to start doing that work, she already knows several sugar baby websites.)

LW needs a good therapist, a bunch of introspection, and a good vibrator. And to hope that their parents don't ask their sister what's going on: The sister could spin the truth as "He called me a whore because I wouldn't help him find one" or even "he was trolling online for sex, then got some kind of weird delusion about me and tried to blackmail me into helping him get laid."