Like a lot of crypto-puritanism it is rather mixed up. He says he recommended Signal because it was easy to use (more consumer friendly I guess) and secure, then says he wouldn't have gone in the direction of making it easier to use and criticises the things that make it user friendly, like using phone numbers instead of usernames.
He says he thinks the protocol is secure, then says he doesn't want it to use GCM because it routes messages via Google who he doesn't trust (fixing that is the point of the encryption) and then talks about an attack that'd apply to any app regardless of whether it used GCM or not.
He finishes with a call to action: "We as a community need to come up with a viable solution and alternative to Signal that is easy to use and that does in fact respect people’s choices ... this tool should not have dependencies on corporate infrastructure"
But like a lot of armchair moralising, he isn't willing to debate the hard choices that go into building successful software. He says it should "respect people's choices" as if Signal is built by people who are disrespectful, he says it should not have dependencies on "corporate infrastructure" as if volunteer run datacenters actually exist, and then says his motivation is avoided paywalls, ignoring that both Signal and WhatsApp are free.
It reads like a collection of talking points rather than a coherent argument.
Signal is unusual because it combines cutting edge cryptography with consumer friendliness and is actually successful. It's pragmatic, not ideological. Crypto-warriors have a long history of producing secure software that nobody uses and then blaming the general public for not getting it; this sort of blog post is just a continuation of this decades long trend.