To add to this, heroin and some other drugs are almost identical in the effect on the brain to an orgasm, and many users describe the intravenous heroin rush as like a "heightened sexual orgasm". Since his power is essentially akin to an instant drug hit to the brain, it's really not surprising that some people describe it as being like an orgasm. But I think most people wouldn't describe having someone inject heroin into your arm as sexual.
It's not been specifically mentioned in game yet, but it's been mentioned in the Discord that Anthony's power affects people differently, essentially with slightly different drug-like effects. Ruth was staring at her hands like some people on hallucinogenics (shrooms for example), Evelyn just got drunk and felt like partying, Moonsong got high and had the munchies, etc. If you're observant and know the effects of some drugs, it's possible to already notice this. Evelyn was simply the first in their group to notice that her effect didn't really feel like an orgasm.
In reality, Anthony is more of a drug dealer than a ho, and I'm sure that'll become increasingly clear as they investigate more.