The author says "TCP sucks", and is promoting his own protocol. Iridium. Which he hasn't even designed yet. That's a bit much. We don't get to criticize his approach.

(Also, if you're designing a communications system, don't give it the same name as another communications system.)

TCP has its limitations, of course. It was designed to work over a wide range of connections, including dial-up, and it does. It's suboptimal for broadband server to client connections where big server farms from a small number of vendors dominate. Hence QUIC and HTTP/2/3. Still, those don't provide a huge improvement in performance.[1] Even Google merely claims "on average, QUIC reduces Google search latency by 8% and 3.5% for desktop and mobile users respectively, and reduces video rebuffer time by 18% for desktop and 15.3% for mobile users." That's marginal. An ad blocker probably has more effect.

The author is worried about the overhead of the three-way handshake, but the overhead of setting up TLS is far worse.

[1] https://conferences.sigcomm.org/imc/2017/papers/imc17-final3...