The Korean Garands’ issues go beyond politics...some were bought by them, while others were MAP aid (i.e. are still US property) and there’s no way to tell them apart. The Koreans lied previously regarding the nature of the rifles that were imported in the 80s, so the Feds have no reason to take them at their word now.
On the other hand, word is a large number of Garands are coming back to the CMP from the Philippines in the near future.
During MAP, the firearms were given to allies or sold at steep discounts. The firearms are their property to dispose of as they wish. As I understand it, the M1 Garands and carbines (several hundred thousand) in Korea were purchased by a US firearms importer (CAI, if I remember correctly) but the physical importation was blocked by Obama’s State Department because Obama hates guns in the hands of civilians and they also consider the M1 carbine an “assault weapon”.