Tor was originally designed by a mathematician working for the US Naval Research Lab (NRL) to provide a way for MI agents to "phone home" safely from the field. It very quickly became clear that if only mil used it, it created anonymity about as effective as Batman on a rooftop backlit by a spotlight -- you didn't have a name but you knew precisely what the agent was about, and where.

So he persuaded NRL to give the project up to open source. Good thing, too, because he was a math geek but not a cryptographer. The two cryptology doctoral candidates at MIT who took the project over chucked his code, and rewrote Tor from the ground up.

Since it's open source, this can be documented. Getting spooky about it being designed for spooks is a red herring.

That GitHub doc vaguely mischaracterizes Signal -- all Signal ever sees is the connection negotiation metadata. Past that point there are no "servers" involved, or data to be retained for future discovery.