Signal might be a honeypot.
Moxie Marlinspike initially developed Textsecure + Redphone for encrypted SMS + phone calls. These were widely used during the arab revolutions in spring 2011, especially in Egypt. Moxie sold to Twitter, became their employee and the services were shut down when people relied most on them. (In 2010 Moxie was detained by feds when entering US from abroad).
Moxie actively undermined development of federation on the server side, insisted in making Signal a centralized service. Long time Google Play Services were necessary with the reasoning of less battery consumption ;-)
To many red flags for me, but DYOR.

PS: You might also take a closer look at Meredith Whittaker

PPS: Similar holds for Proton Mail which was never invented at Cern.