@queserasera Exactly.
Unless a system is decentralised (without centralised signaling), it really comes down to whether or not you trust the people involved. It could open source (but can we verify that the source you see in the repository is what’s running on the server?), it could be end-to-end encrypted (but if the centralised server controls the ends can we be sure which ends are included?), etc. (I mean, of course, if those things don’t exist as a minimum, then no to begin with.)
So it really comes down to do I trust Meredith? And – although I’m usually loathe to unless I’ve met someone personally and looked them in the eyes – from everything I’ve seen of her talks and work, I do, yes.
As you mention, the only trustless alternative is the end-to-end encrypted peer-to-peer messenger you’re running on your own hardware at home. And yeah, congratulations if you’re one of the three basement-dwelling geeks doing that in the world.