A few possible reasons, the most obvious being grandparent is disclosing a possible source of bias. Also it could look suspicious if grandparent gets the job a

A few possible reasons, the most obvious being grandparent is disclosing a possible source of bias. Also it could look suspicious if grandparent gets the job and at some point in the future someone looks back at this comment. If in doubt, disclose. Especially in the tech industry, that's what Gamergate was actually about.