Why would it be impossible for Signal to decrypt and re-encrypt on their server while pretending to be "peer 2 peer encrypted" if we don't know what's running on their server? What's more: we don't even have the source of the client binary running on our phone.

Also "which any nation-state can do" is an interesting angle.

Let me put that differently: why would Signal NOT be a honey-pot operated by the CIA/NSA/other? Sounds almost too easy to not be true.

Simplex shy away from User ID, which means you are giving up something in exchange (notably no message encrypted-at-rest in their server): then the government can access the message contents from Simplex server.

It says so on their website:

"Only client devices store user profiles, contacts and groups; the messages are sent with 2-layer End-to-end encryption."

What it does NOT say is that message content remains encrypted on their server like Signal does.

It is like time, money, resource: pick only two. But in secured communication, that would be personal anonymity, personal privacy, and personal security: only can pick two.

https://simplex.chat/#how-simplex-works