This says that the drug creates the ability to relearn something, but the learning process itself is of course mediated by the setting provided - learning is always about interaction with the environment. This has nothing to do with weasel words, it simply illustrates the mode of action.
Or rather it can't really be studied in natural (uncontrolled) setting, given that it's a heavily controlled substance. You just can't give it to people and let them run loose. You also can't just collect their opinions on experience with otherwise acquired MDMA, because it's cut, altered, often other substances or a mix of substances.
Also as a scientist you do not want to be seen as supporting self-medication with with illegal and dangerous (MDMA has low therapeutic index) substances.
> may be linked to the psychedelic’s ability to reopen a “critical period” in the brain for social reward learning. That's a lot more weasel words than the headline.
I see it more as a careful scientist wording, given that it's really hard to study psychedelic drugs.
Is this referring to something explicit? I'd think it's certainly possible it could work in many, but only certain settings have been or can be studied, for specific definitions of "study".
I think the ultimate source of the article's claims is this study, but there might be others I am not aware of - the research of psychedelics has exploded lately.