Earlier quoted context omitted.
I think if you consent to go to the sex party, you consent to physical romantic activity, you consent to taking the drug knowing your context and what the drug will do, and then you consent to sex throughout the experience, it's hard to see how it's anything but consensual. If you have a colonoscopy done, the medication they give you will make it so you don't remember things or (I hope) feel things, but, my doctor to…
It would be non-consensual if you didn't give affirmative consent. However, reading this, it seems that affirmative consent was given at all times, first to taking drugs and then to making out (or having sex) so this article is basically just a hoo-hah over consenting adults engaging in drug-enabled group sex.
In might be consensual in the sense that everyone said yes, but there’s a known balance of power. Sounds like coercion and naivety.