On the other hand, "natural language aptitude" as measured by Modern (modern = ca. 1960s) Language Aptitude Test, which they used in that study, doesn't actual

On the other hand, "natural language aptitude" as measured by Modern (modern = ca. 1960s) Language Aptitude Test, which they used in that study, doesn't actually predict success in language acquisition. The test scores correlate with ability to perform well at _early_ phase of language curricula – but this is exactly the phase when the learners are still using the "general processing mechanisms" to process language, and not the mechanisms specialized for language that get engaged when they gain fluency years later. Sadly, this is underappreciated in the general psychology and linguistics community. Some researchers in Second Language Acquisition research community are more concerned about this kind of mis-interpretation and confusion of different meanings of "language skills/aptitude".