They didn't say "reality must be wrong". They said that their initial hypothesis (that significant changes would be observed after 21 days) is probably wrong, so they implicitly proposed a second hypothesis (that significant changes occur after e.g. a few months).
None of this is remotely contemptible.
Pretend you're an immortal alien conducting a study with the hypothesis, "humans are mortal". You observe that your subjects do not die after 21 days. Do you conclude that humans are immortal? (I hope not. It's much better to conclude that humans don't usually die after 21 days in this particular instance of extraterrestrial captivity.)
OK, fine, they didn't literally say "reality must be wrong", they just thought it, probably. The attitude stinks. And I say it is remotely contemptible. Perhaps I'd go as far as to say moderately contemptible.
It's a fair point about the aliens. They are presumably mortal themselves, they have expectations about lifespan. Something about the mind not being a blank slate, it's hypotheses all the way down, can't escape preconceived ideas. Sure. Except you can try. You can be more impartial than you otherwise might be, when you're aware that there's something to be partial about.
In the case of smartphone bans, the viewpoint is almost politicized, like whether you're down with the tech bros or think they're evil. Researchers should know that, and thus should be very coldly objective. Here they expect the degradation of mental function, why? That's not something well-understood like mortality. It's probably something there's a great wobbly mass of very questionable psychological research about - low attention in school and degraded working memory due to what they may well call "screentime" - and they've just gone along with it like it's established. Why is known evil thing not acting sufficiently evil to meet our narrative? Must do more research until true.
Another sketchy part of doing this research is the subtext that smartphones lower the mood entails therefore ban smartphones in schools. That isn't a science-based decision, it's a decision to trample on the kids' rights for their own good: science can't guide moral choices. But the only reason to scientifically establish the first part, the fact, is for the purpose of advocating a ban.
If you think children have a right to smartphones in school, then your priors are just really out of line with anyone who is actually concerned with the well being of children.
None of this is remotely contemptible.
Pretend you're an immortal alien conducting a study with the hypothesis, "humans are mortal". You observe that your subjects do not die after 21 days. Do you conclude that humans are immortal? (I hope not. It's much better to conclude that humans don't usually die after 21 days in this particular instance of extraterrestrial captivity.)