i would guess that someone gave them his name
then told them how to trace back to where they wanted to start their story
about their mighty detective work
happens all the time
they even have a name for it but i cant remember it
they forgot to put it in the patriot act or the updates
so they just had a judge declare the 4th amendment invalid–again
signal is a private company that can probably sell anything you put on it
must read the 837 pages of lawyer speak terms of service to be sure