Re: Oh dear, how sad, never mind.
I very nearly downloaded Transmission for my Mac this weekend. The reason being that I've just bought a Pi 3 for my 7 year old and was downloading Raspberian. There's an option for downloading via bittorrent. Since the http download was going very slowly, I considered downloading Transmission and using that instead. In which case, I'd have ended up with this malware on my Mac.
There are other open source projects (Libreoffice springs to mind) that provide torrents for downloading, so there are certainly legitimate uses for installing Transmission.
So I hope that you're downvoted to the pits of hell, where you obviously belong.