But we don’t know for sure they did it (just an accusation we are building from), also, if this is in a building, it may be on a shared network. For example, I have an office in Dallas that co-locates several companies. There are common areas with open wifi (break rooms, shared conference rooms). This may not be this specific law firm but someone in a company who shares the building. It also may not be a direct employee but an IT service employee, etc.
Most likely you are right, but I’m not much on jumping the gun until we know for sure.
They’re lawyers, and well to the left apparently. They already know they are scum. That said, it’s always more effective, when trackig varmints, if you don’t make a lot of noise or stink.