I believe that bias is almost inevitable when using support material. In the book, it is unpacked that people use statistics to support their thesis quite often and manipulate statistics to correlate with their bias. Even a very open-minded and level-headed person finds themselves using bias to amplify their speech quite often. I believe it is potentially easier to be more unbiased in an informative writing or speech, but there are still so many different views and different takes on topics to the point where even when you're unintentionally being biased, it still manages to insert itself in someone's speech. In chapter 5, the book states that people can unintentionally get something wrong and misinform the audience. I don't believe that bias is always bad because it is okay for someone to have their own beliefs and in writings or speeches that are intentionally persuasive, having a bias is the foundation of your claim more often than not.
To sum up, I don't believe that bias is always a bad thing to include in a writing or a speech, but I do believe it occurs in a speech or writing more often than not.