Earlier quoted context omitted.
Anything as subjective as one's own mindset interpreted by oneself is incompatible with the scientific method in the first place. It's not the right tool for the job because it is impossible to objectively measure the results. That does not make those results any less real.
"Real" in what way? I would say that something is definitely real if I can agree with other people that it's there, while other things can at best be put in the "maybe" pile. Whatever you experience while meditating, other people won't be able to experience it, so it can't go in the "definitely real" pile. So the fact that it can't be studied scientifically definitely does make it less real, in the sense that your ca…
But notice that this isn’t really private to a person.
How are we sure about external events like a ball falling down? Are they not processed by our minds and then expressed in language. A ball falling down is fairly standardized and accessible, but for other events there is a lot more background which is needed. But human experience and culture is filled with phenomena which require a much larger shared context - which is acquired after walking in a shared territory. Like long time explorers of the seas who can have a a conversation on far away lands.
Explaining many current physical concepts or how to interpret the experiments which are conducted at a non-superficial level requires years of training (leave alone research). Even someone who finishes high school algebra is at a rarefied stage compared to people thousands of years ago.
Getting a shared context in meditation related explorations might actually require much lesser time.
For similar reasons, negative stages itself have been meticulously documented in manuals like Visuddhimaga which are referenced in the books mentioned in the article.(fwiw, my 2 cents on the article - maybe instead of promoting intense concentration on sensory phenomena, love based practices like bhakti or metta might be a better popular practice).
A good counter argument is that in the physics example there are gradual stages in learning where at each stage you can test what you learn and match it with the world, not spend 15 years of education to get to QFT and then match with experience.
But that ladder is present even in the case of traditions which explore the mind.