That's the correct question to ask, and the short answer is "no."
Non-self means that there is no sperate, unchanging self. You are a constantly changing phenomenon that has arisen due to causality.
You can see how the two might be correlated, but it's loose at best.
There may be other better questions on the inventory, but that's the example given in the article. I also noted that they didn't mention practitioners having scored higher on narcissism, but only on "self-enhancement". (I haven't read the actual study, so this could all just be bad reporting.)
https://eprints.soton.ac.uk/420273/
Ego is measured by answering questions like ...
> “At the moment, I have high self-esteem” (1 = does not apply at all, 7 = applies completely).
I'm unconvinced that vague self-reports like this have any useful meaning.
I wonder, is this what ego means in Buddhism? Also, is this what ego historically meant in Buddhism? For a long time, people in Buddhist communities would call you crazy if you meditate. Having followed one theological course on Buddhism at the Vrije Universiteit Amsterdam, I am convinced that whenever you study meditation, you need a theologian specialized in Buddhism next to you in order to see if you're comparing the same constructs.
I also wonder if only meditation is supposed to have an effect on diminishing the ego, according to Buddhism. Buddhism in general is much more than only meditation. It's probably analogous to teaching people to pray and through prayer they'll figure out the 10 commandments. The result is interesting in the sense of how meditation affects someone from a western culture (someone like me). But it is dangerous to imply that this applies to Buddhism. They could've easily circumvented that by putting the scientific terms in the title.