Advocate for reality: they don't mean shit in bigger scheme of things since virtually nobody uses them. So secret groups put less effort into them. Yahoo, Gmail, Lavabit, various IM's... all were in the Snowden leaks as SIGINT-enabled through taps, black bags, or "FBI coercion." If Whisper got that important, I think we'd see bad stuff happen to the company or Moxie.

So, enjoy the added protection from nation states of low uptake if you're using it. :)