In other words, he thinks that not being biased is the automatic default.
I think this is what many inductivists think: that all the theories they make up and claim to have induced are not just bias talking. And why do they think it's not bias but rather a hint coming from the evidence itself? Because it can't be bias because they didn't intend any bias or do it on purpose. Simple as that.
But actually epistemology/reality is the other way around: everything is biased by default (a lot, not a little), and it is only with great care and effort that we can get anything that isn't biased.
It's as Feynman said: it's easy to fool ourselves, and science is what we've learned about how to not fool ourselves. Or in other words, bias is the default and the scientific method consists of doing everything we know how to in order to reduce bias.
You can tell there is a lot of bias to overcome because of how careful scientists have to be to get good results. It's not that the scientists are bad people or anything like that, it's simply that avoiding bias takes skill and effort not just a lack of bad intentions.
David Deutsch says about this (quoted with permission):
It's the intentional fallacy. If something is bad, a bad person must have done it. If something is biased, a biased person must have done it. And therefore if we are all pure and unbiased, we are infallible.That reminds me of *early* induction. According to Popper (with textual evidence and good arguments), Bacon's conception of induction was a bit different than what you usually run into today. The main idea was to *purge your mind of bias*. Then you can read nature like an open book and make zero mistakes and finish learning all of science in a few years.
This is (again via Popper) building on the *original* meaning of induction which comes from Aristotle (who falsely attributed it to Socrates) which was about maieutics. The idea is, very roughly, that the truth is trivial (and already inside us, I think) and the only obstacle to the truth is therefore bias.
 How do you know what is a bias and what isn't? Easy. It's all bias. Just empty your mind completely. That's Bacon's way.