The President admitted to the crime in the documents that he submitted. The case is proved by what he said that he said.
Ultimately, the President is his own whistleblower.
Realizing his mistake, (of admitting to the crime that he committed), he is furiously trying to create a personality that he can attack. He can’t attack his own decision to release his own documents, so he needs a “liberal” that he can hold up as a boogyman.
The whistleblower’s task is now over. The President admitted to the crime. No need to try to explain that the whistleblower didn’t write the documents that the president released, (which is what he is going to try to convince people happened).