I think the difference they alluded to is that they manually vetoed new users, presumably based on their self-declared goals and ideology, whereas Signal etc are neutral platforms.
Yeah I didn’t elaborate since this was explained elsewhere in the thread.
The A/I vetting was in the form of a form asking why do you want A/I email or blog. You could write anything in it.
Meanwhile, Signal requires a phone number, so it knows much more about your identity than A/I did.