Drew DeVault doesn't trust Signal because its Android incarnation uses the Google Play Store --- the app market virtually all of its real users use --- and not F-Droid. DeVault would also like it if Signal would interoperate with other chat programs.
Instead, DeVault would prefer that you use Matrix, a system for which end-to-end encryption is (according to its own website) "in late beta", offered on a select subset of clients, and "not enabled by default"†.
This argument is clownish and we should be embarrassed it's on the front page.
There are people in the world that want to sysadmin their phones. It's a life choice they are free to make and I don't hold it against them. But the vast, overwhelming majority of users do not want to make the app market on their phone work more like Debian and less like the Play Store. Signal, to put it bluntly, does not care about the desires of the phone sysadmins. Even if they caved to the sysadmins, the application would, for virtually all its users, be no more secure. This bothers DeVault a lot, enough that he's constructed an entire psychoanalysis of Moxie Marlinspike to explain to himself how it could possibly happen that someone else on the Internet doesn't agree with him.
Also, just as a note to DeVault: the point of end-to-end encryption is that you don't have to trust Signal's server. All it does is arrange for the delivery of messages, which are secured client-to-client. Compare Signal's server to Wire's, which --- last I checked --- retains a record of every pair of users who have communicated in the past.
† When this was pointed out downthread, DeVault responded: "[o]ther alternatives (which I have not reviewed in depth) include Tox, Telegram, Wire, and Ring". Telegram is a particularly funny reference to make, because not only is E2E not the default there, but --- last I checked --- it can't even do E2E group chat. Telegram's owners are adamant that TLS is adequate for group secure chat.