Not to mention: if everything is encrypted using your password as a key, how do your friends see your posts? Are they encrypted for each friend with that friend's public key?
That sounds about right. However this is a closed-source project, so I don't see why it would be picked up by privacy enthusiasts.
I figured it was likely in the app, but for an experiment like this, that appeals to many of the ideals of an open source philosophy, I'm less likely to bother installing it if I'm unaware that it's an open source project.
Obviously the appeal ultimately needs to be greater than just being open source, but that initial bump can't hurt the outcome of the experiment.