On its 10th anniversary, Signal’s president wants to remind you that the world’s most secure communications platform is a nonprofit. It’s free. It doesn’t track you or serve you ads. It pays its engineers very well. And it’s a go-to app for hundreds of millions of people.
They do have the capability to not have the data requested. If they are not required by law(and it seems they aren’t), why store any data? They may have to provide data of the sessions that are active right now but it’s unlikely.