[stormbrew]

The answer to this, for something like btsync, is that you shouldn't really be trusting the servers outside your control to begin with. That's the whole point of these systems as opposed to the usual cloud model where you're throwing plaintext up to a server and hoping their security model holds.

If the client software is all that's ever supposed to see plaintext, being able to see source allows you to confirm that that is (probably) the case and then compile it yourself rather than trust that they haven't thrown an extra step in that backdoors it.