It looks like Signal isn't as open source as you thought it was anymore

So the client is open source and guarantees end-to-end encryption regardless of what the server does. Ok, then I honestly don't care. Why should I?

I use Signal for its safety characteristics, which as stated are apparently ensured by the client regardless of what the server does, not because of the server, and I continue to agree with Moxie that federation is a white whale that doesn't solve any regular person problems.

1) Much (most?) of the time, participants don't get to verify their safety numbers, and in those cases you are at least trusting the server to deliver your messages to the right client. There's a potential vector for man-in-the-middle attack (witting or unwitting) on the server side which shouldn't be dismissed here just because users are "supposed to" verify safety numbers.

2) Their behavior regarding server software might be predictive of their behavior regarding client software in the future. Given network effects, it might not be so easy to leave the Signal ecosystem in the future if your social network is on it, so it's worth knowing right now that it's possible that in the future the client software will also be closed-source.

This is where I feel a little unsure about Signal. It wants access to my contacts, and so it is possible to poison my contacts to get a rogue recipient into Signal. I would like a Signal in which I have the option to manually add contacts. Ideally a hash or key exchange or something, maybe a la PGP...