Precisely. It is doubtful that AFIP is currently, or necessarily will in the future be tracing Expat assets through this mechanism, or similar, or asking Migraciones for records of Rentistas. But, in the end, we can only ever guess at their approach, so it is a good idea to be aware our individual risk profile, and do whatever we each think necessary to manage the risk.
Some on this thread (and another thread where the issue cropped up) have expressed complete confidence that AFIP would never target Expats and their wealth: not a confidence I share, but it is a legitimate point of view. Others have argued you could, if caught, pay a lawyer to litigate it into oblivion: not a position I would want to find myself in.
It is useful to follow news stories on the Bienes Personales tax, because the situation could change over time. For better, or worse.