I fear signal has to be mentioned a thousand times from all directions before they "trust" it.
Yes. A thousand times yes. The risk profiles humans naturally adapted to are not well aligned with the artificial risk profiles we see today. I can't fault someone for not transcending their own natural instincts, because heaven knows I can't.
Sure. That's one possible vector. Is it "Open Source" software? Yes, they accept contributions for the community. It's is "Libre" software? No, they depend on closed source software.
I'm trying to illustrate that the definition of "open source" can be weaponized for no good reason. Dismissing Signal because it doesn't fit a narrow definition of "open source" makes everybody less secure. I have a hard enough time convincing my non-tech-savvy friends to switch to Signal. There's a snowball's chance in Hell I'll convince them to use something even more obscure.
Not open source
There are lots of good reasons to be upset with how Signal produces builds. And maybe Signal has no good reason why they keep opaque dependencies. But by every common definition of the term, Signal is open source. Being on FDroid is not the definition of open source.
Please don't gatekeep. There are better ways to criticize Signal. This is not one of them.
Non-sarcastic reply:
Horseshoe theory isn't so much about "the far-left is the same as the far-right" as it is about "all authoritarians derive power from the same human instincts" and the further left or right you go, the more authoritarian you have to be in order to achieve the social narrative you're aiming for.
Edit: misplaced word
If it's used as an identifier to link together rows from different tables. Also known as "joining" tables. SSN (with birthdate) is a unique identifier, and so it's natural to choose as a primary/foreign key.