Horowitz says in his lawyerly voice, that he couldn't find any "documentary evidence of political bias" meaning he couldn't find a text or e-mail stating "I'm doing this out of political bias" and when each person was asked "did you make these omissions, these mistakes out of political bias", their answer was "no, I did not" and that ends that other than to say Horowitz was "not satisfied with the answers he got".
Then when asked if he could rule out that all these people who lied and broke the law were motivated by political bias, his answer was no, he could not.
I accept for now ( until Durham has the final word ) that the "opening of the investigation" had the legal, FBI policy predicate for "opening the investigation". And that's were the lack of political motivation ended as evidenced by an FBI lawyer risking his job and his freedom because he will be prosecuted and found guilty of a very serious crime, just because he hated Donald Trump like so many others in the Deep State.
Horowitz knows there was bias, he is saying that he couldn't prove it with uncovered documents with an admission of guilt in writing. He leaves it up to us to read what he has written and use our own judgement as to whether the FBI made those 17 errors in applying for FISA warrants because they were over worked and merely tired or they were motivated by hate and political bias. I don't buy it and neither will the jury when more than just Klinsmith the FBI lawyer who changed the wording in a document that was submitted to the FISA court are put on trial.