"The Bronze Star Medal (BSM) is a United States Armed Forces decoration awarded to members of the United States Armed Forces for either heroic achievement, heroic service, meritorious achievement, or meritorious service in a combat zone."
His son likely received it for meritorious service... There is typically a citation for these awards.
As I understand it, the BSM was the “Been There - Done That” award for service in that conflict. The “heroic service” attribute of the medal would be indicated by a “V” device on the ribbon & in the citation.