I believe the bias is unavoidable and not always a bad thing when using supportive material because being biased come natural to everyone. I would say that being biased is not the goal and you should strive not to be when using supportive material but it is going to happen. Like for example if I was doing a speech over the Bears, I am obviously going to be biased because I am trying to get my opinion a crossed but I do not used my research in a biased way where it makes me not creditable.
I am biased against the Bears, yet I was still not hesitant to listen to your speech because you used (mostly) unbiased material to support your claims. I agree that bias is hard to avoid but we should strive to avoid it.
I like that you said that you shouldn't strive to be biased and that shouldn't be the goal.