Yes, this is a compromise on the CIA triad. It prefers integrity and confidentiality over availability.
That is a fine decision to make for a security-minded app, but signal has always presented themselves as a full alternative to SMS and other messaging systems where availability is prioritized over confidentiality and integrity. It should really be made more clear so that users are making an informed decision. They could also do wonders for the user experience by having the app inform the user of the problem and how to remedy it.
Yeah, but I wouldn't call SMS super available either since it relies a lot on the ends too. Had a lot of those drop when I traveled. Something like Facebook Messenger has a whole server storing messages, so it's solid, you'll receive them later even if your phone breaks.
That is a fine decision to make for a security-minded app, but signal has always presented themselves as a full alternative to SMS and other messaging systems where availability is prioritized over confidentiality and integrity. It should really be made more clear so that users are making an informed decision. They could also do wonders for the user experience by having the app inform the user of the problem and how to remedy it.