I assume that he came to the conclusion that he isn't qualified to look for it - without massive familiarity with the code trying to find something that was int

I assume that he came to the conclusion that he isn't qualified to look for it - without massive familiarity with the code trying to find something that was intentionally hidden would probably just be a waste of time he could better spend. Disclosing the allegations so those with a reasonable chance of finding the thing if it exists is, basically, the responsible thing to do here.