Like others have said on threads about Beeper, it is a great app, but will just be a cat and mouse game for eternity, until it gets shutdown or a lawsuit is filed by one side. I don't expect this to be the last outage.
This is absurd. It's like reverse engineering your cable provider's decoder box, making a business to sell the pirate copies and then going back to the cable provider to nag about outages or whatever. In what reality is this good idea?
Also, we're talking about private messages, you can't "just" introduce a third party to have them copy-pasted-as-a-service on some shady devices.
If I wanted to send insecure messages to friends who don't own an iPhone, I'd send an SMS. But really just WhatsApp.