Advising people to use messaging systems that you know to be faulty because they optimize in some other non-personal-safety area like "federation" or "open standards" or "compatibility with email" means that you are putting your own aesthetic preferences above other people's safety. It's simply malpractice.

I really think people would be safer communicating their sensitive messages on Delta Chat than on Signal. Both are encrypted securely enough, and the endpoints being compromised is probably the biggest threat in both cases, but with Signal there is more metadata (the phone number) and you're almost certain this is being farmed on a massive scale (as opposed to Delta Chat).