Another reason: all of the folks on that group chat have legitimate reasons to have contacts on their phone that would be outside government apps. Foreign leadership. Journalists. Etc.
Signal is likely to be one of the main ways of communicating with those.
It wouldn't actually. The contact in his phone (incorrectly added by Apple AI from a forwarded email) would be the same regardless which app he was using.
Instead, Signal (and this forked version) would have to do its own independent contact management, maybe based on in-person scanning of QR codes plus web-of-trust.
If only it would a- not ask you to access your contacts and b- accept when you say no instead of saying "we'll ask again later" (and then, indeed, asking again later).
Signal is likely to be one of the main ways of communicating with those.