One of the employees was apoplectic at the actions of the sys admin and had accused him of violating her privacy by doing this. While I do not recall which party initiated legal action against the sys admin that led to his arrest (i.e. the employee or the company), the bottom line of the story was that the FBI employee (and, by extention, whichever judge was involved in adjudication the case) considered the act of a sys admin accessing password hashes placed under his care to be a criminal breach of privacy regardless of his intent being to improve his company's security against password stuffing attacks.
Assuming the FBI employee didn't just make the whole thing up (which I have no reason to believe - there are a lot of tech-stupid judges and, especially a decade ago, tech-stupid FBI employees), it might be prudent to pass this by your legal team before checking for password hashes for your employees being in haveibeenpwned.