The concern is more linguistics in this case. Yes, the article brings in physics but it’s not about physics, per se. Therein lies the challenge.

Depends on what you mean by studied. I’m not going for a degree in it or anything, but I have been following research and engaging with physics education for about 15 years. But what does that matter? Let’s say physicists routinely use this extra broad definition of physical- that’s great for them, but their definition does not define it for other disciplines. So here we are in a philosophy subreddit, where we can reasonably expect something more narrow, so as to not automatically apply to any observable.

Saying time is physical is still a model of sorts, and without an extraordinarily broad definition of physical I would not agree that the experiment outlined suggests physicality.

More accurately, we can verify the accuracy of a model (general/special relativity) that treats it as physical. But even then, that model is incompatible with another successful model (QFT) which does not treat time as physical. So it continues to be a bit of an open question.