Yes, if they have access to additional outside data sources or perform some minimal fieldwork to verify their results. This is precisely why the Census Bureau must seriously address the threat of disclosure and apply a comprehensive and coordinated program of disclosure avoidance.  

The Census Bureau has the only copy of the confidential microdata, but an adversary could have access to many different outside data sources. Unless we protect the data, an adversary could independently confirm their reidentifications with reasonable certainty.  

As the volume and quality of outside data sources such as names, addresses, and birth dates grow and improve, so do adversaries’ presumed and actual matches. Our analysis of 2010 Census reidentification vulnerability used a large database of commercial information available at the time of that census. The risks associated with using 2010 Census disclosure avoidance methods today and into the future will only increase.