To me it seems most likely that Goldberg was in Waltz’s contacts phone app, but Waltz did not realize that the Signal phone app ingests all your contacts when y

To me it seems most likely that Goldberg was in Waltz’s contacts phone app, but Waltz did not realize that the Signal phone app ingests all your contacts when you install it and log in. It’s incredibly common for senior officials and senior journalists in DC to have each other as contacts. DC runs on relationships and people reflexively hang onto any phone number or email they perceive as valuable. And it seemed weird (to me at least) that such a privacy-focused messaging app would just “suck in” all my contacts the first time I turned it on. I can believe that other people would not realize this happens. And thus not be vigilant about inscrutable usernames like “JG” that might be duplicated.