'You have to go back in history, at least to the time when the devs dropped sms encryption and even earlier.
The main developer, in a matter of weeks, had turned from someone harassed by the TSA into a receipient of a major government grant ($13 mln). Then he received lucrative contracts with the “greatest” bastion of privacy, Facebook and affiliates. You don’t get that by accident. You get that by providing your own significant part of the bargain.'
https://forum.f-droid.org/t/we-can-include-signal-in-f-droid...
Just saying it's not the most unfounded theory out there.