I looked up the Open Technology Fund on Wikipedia and it has no relation to the CIA. well, except that its parent agency (Radio Free Asia) is part of the US government like the CIA is. they don’t seem to work together at all, and they’re under the purview of two different branches of government
besides, as other commenters have said, they’re open source and they’ve been audited. anyone can build the client themselves (with any potential backdoors removed) and set up their own server. would the CIA allow for that?
It’s Cockney rhyming slang. If you want to come up with a slang term for a something, you take something that rhymes “yank → septic tank” and then cut it down “septic tank → seppo”