I think the rule regarding Pirating related stuff is because, due to the ease of which one can start pirating, it's very easy for any topic about piracy to lead to people being recommended pirating software, or the best sites for it or tips or what not.
Discussing piracy is too easy to lead to people spreading or promoting piracy.
I'm sure there are people on these forums who have pirated. And they'd probably have no problem discussing the way they do it. But then that leads to more people learning how to pirate and before you know it, it seems like this forum advocates piracy.
Discussing drugs is slightly different because regardless of what is discussed it's harder to show people how to find illegal drugs. You could discuss where to find drugs, but that would likely get you banned. But that sort of thing is less likely to come up in discussion of drugs, whereas in discussion of piracy you're much likelier to mention where to find the resources to pirate, since it's all on the internet.
If you could download drugs then maybe discussing it would be banned on here.
Plus, take into consideration that Badspot is a game developer and has produced a number of things online which produce revenue for him. Discussing piracy only promotes people cutting into his earnings.