This is not an essay about whether science "is" a religion, or how "religiony" it is.
He's just arguing that the way science is treated by the general public has many specific negative features, and that many of these are held in common with religion. And he's quite clear about what those aspects here.
It's poetic language, and arguably unnecessarily inflammatory, but it's not the main thesis of the essay. Specifically: If you identified a key distinction between religion and scientism that we all agreed was "required" by any good definition of religion but wasn't found in scientism (say, an afterlife, or a story for why bad things happen to good people), that wouldn't much affect the validity of the essay.
If you remove the analogy to religion I don’t see how any substance remains. For example the essay present subject experts as problematic through the analogy to high priests. But if you remove this analogy it is just common sense that someone who have studied a subject knows more than someone who hasn’t.
I mean a carpenter knows more about carpentry than a random person - how is that controversial or problematic? But lets call carpenters high priests thereby implying carpentry expertise is somehow suspect. If you try to lecture a seasoned carpenter about carpentry they would probably also call you an idiot in more or less polite words. I guess that just proves how carpenters are like high priests jaleously guarding their status?
The whole essay is just riddled with falacies and strawmen. For example the fact that someone have tried to study war scientifically apparently means this makes war acceptable. How does that follow? Never mind this completely ignores the history of war and justifications of war which is much older than science.
A criticims of scientism and its derived pseudo-religions like nlp, scientology, transhumanism, the singularity, simulation etc would be very welcome, but the analysis need to be coherent, otherwise it is no better.
He's just arguing that the way science is treated by the general public has many specific negative features, and that many of these are held in common with religion. And he's quite clear about what those aspects here.