Maybe he is afraid some republican will leak the whistleblower's identity.
Whistleblowers are not guaranteed anonymity. That's not how the whistleblowers are supposed to be treated throughout the entire process.
Knowing who the person is sheds light on the person's history, politics, motivations, associations, and so on. Those are all important factors in determining credibility.
Keep him in the dark avoids all those embarrassingly negative factors from being known.
You have an erroneous belief that whistleblowers can be shielded from being outed beyond the initial review. That's true up until the point their accusations become a full fledged investigation. At that point, the people being targeted in the complaint have a right to confront their accusers. Nobody should be afforded the protection of anonymity during a public investigation, especially a criminal investigation.
Whistleblowers who do come forward, anonymously or otherwise, often request that their identities be concealed.
There are just too many headaches involved in continuing to work in an environment in which they are known to
have been a “snitch”. But can a company agree to keep the person’s identity a secret and still conduct a thorough
and fair investigation? Unfortunately, the answer may be no.
“The company can’t promise that the whistleblower’s identity won’t be revealed because there are certain instances in which it may need to be revealed,” says Lisa Noller, litigation partner with Foley and Lardner LLP. “For example, if the company is cooperating with the government, then the whistleblower’s identity may need to be disclosed because the government requires it.”
And then there’s the chance that others in the company may be able to guess the whistleblower’s identity. “You might need to disclose detail about the nature of the complaint, for example in an SEC filing, that somebody will be able to figure out who the whistleblower is,” says Noller.
https://i-sight.com/resources/can-whistleblowers-remain-anonymous-during-an-investigation/Our system of justice is predicated upon the notion that all parties are treated equally under the law. Giving one party anonymity offers an unfair advantage to that party.
People know what becoming a whistleblower means, most often than not leaving the organization they are reporting. Who really believes they can continue working in a place they see as needing to be reported to an outside investigator?
What do you think is going to happen to the whistleblower? There are protections in place to prevent/punish retaliation.