I don’t think it’s especially likely that you’ll find consistently interesting, well-reasoned discussion through any platform bringing together anonymous strangers in an ephemeral manner.
I think consistently interesting discussion has shared stakeholding as a foundational aspect - participants need to actually care, either because the discussion is a product of some commitment they’ve each made (e.g. reading something for a book club), or because the participants are familiar with each other and the outcome tangibly matters (e.g. a physical town hall meeting).
Otherwise, I think you’re more likely to get what you’re looking for from adopting some tangential hobby and having those discussions with the friends you get through that.
It’s not as though the existence and mechanisms of piracy are a coveted secret. There’s a decent chance that they’ll learn about and attempt it independently, and the method they learn about online might expose them to greater risk than if they did it with more consideration.
On that basis, I think that knowledge transfer is at worst harm reduction. If it’s immoral, which I don’t believe it is, then at the very least your intervention could prevent them from being preyed upon by some copyright troll company when they do it despite your silence or protestations.