Not a fatfinger
Discussion
I'm not an expert, i think the probability is 50/50
I use signal daily. It is not normal workflow to add people to a group chat.
Ok, now the claimnis that Waltz created the chat to begin with, implying he may have inadvertently added the Atlantic reporter when selecting members. Still, this is highly unlikely. Why would the reporter be in his signal contacts to begin with? I still don't believe it.