Yep, that's it in a nutshell. This isn't a Trojan in the PC sense, because all you have to do on a PC is just click on a file... POOF! there goes your drive.

Anyone stupid enough to first, download a piece of software from an untrusted site (porn? trusted? give me a break!), then actually install that software manually (that's the difference between Mac and Windows - Windows never even asks you), and finally provide an admin password to an untested piece of software... They basically deserve anything they get.

That's not a Trojan Horse, that's the Trojans opening up the horse, looking inside, seeing the Greeks hiding in there, and then going 'Come on in, I'm sure you boys don't mean any harm!'