I've had a few conversations with [security nerds more familiar with telecom] since SignalWire broke embargo.
The "everything sucks and there's no motive to fix it" was a synopsis because, frankly, those conversations get really hard to follow if you don't know the jargon. And I didn't feel like trying to explain it poorly (since I don't understand the space that well, myself), so I left it at what I wrote.
(I didn't expect Hacker News to notice my blog at all.)