I dont even program and i could've told them it was probably a placeholder or default value lol "durrrrrr lot of people in this database were born at the exact same time on the same day in the same year that predates electronic databases, gotta be fraud!!1!1!11"

More likely they nuke it due to that lack of understanding.

2016-2020 was the age of too stupid to break everything. Now we're staring down the barrel of "The files are in the computer?" But the entire US government is the computer.

They'd probably just delete the Cobol code since "nobody would use that old stuff anyway".