@nemobis @evan One could start the argument by just asserting that the whole point of E2EE is that trusting the clients on both ends is "enough", in the sense that it makes no difference whether the channel and the server are compromised.
With Signal one tends to trust the client because it's open-source and the releases are (claimed to be) reproducible. With Whatsapp... well maybe you could inspect its traffic with mitmproxy idk, but ultimately there's no reason to trust the client