Threw away Transmission as soon as I read this (even though I was running a old version), my trust is pretty much gone now, never installing it again.
Shame because it really was a nice app.
Transmission was and remains my favorite torrent client on OS X, although I still like the torrent information presentation uTorrent had, and I still will run my old pre-adware 1.6.4 if I want more detail on a swarm.
Given that older versions still work, it seems exceptionally silly to delete an old version because of a site compromise.
So clone the last release version you trusted, build that from source and be happy?
The current version could be being compromised this minute for all we know.