[int_19h]

I have switched quite a few casual users to Signal by now, and in my experience, none of them have paid any attention to those regardless. They don't even bother asking the person through some other channel - just confirm the new number.

[joshuamorton]

Assuredly, but most people aren't actually that concerned about state sponsored attacks on their communications, and for those people Signal is still as good as (or better than) PGP email, but they can safely ignore these notifications because, well, the likelyhood (and the risk due to) a state sponsored attack is relatively low.