If you want to write fiction, you can only use standard bias-free English all the time if all your characters are standard bias-free English-speaking persons.
You will find this difficult, because although quite a few people speak standard English, the only people who are bias-free are dead. Though many people may try to be, anyone claiming to be actually bias-free is either a fool or a liar.
All human beings are influenced by their upbringing and personal experience to see the world in a way that is peculiar to themselves, and that is assuming they all start with relatively similar perceptual apparatus. (Obviously if you have unusually good, unusually poor, or just different sight, hearing, taste, touch, smell or ESP, your perception of the world will differ from standard). This doesn’t mean your way of viewing the word is right or wrong, or even that there is a right and wrong, it just makes you honest when you acknowledge that it’s your way.
In addition, our senses are not set up to show us how the world is, but to show us how the world is in relation to ourselves. As an example, both the timing and the volume of a sound will differ according to how close you are to its origin, whilst if a light is associated with the sound, the light will reach a distant observer first. I well remember, on my first visit to a cricket match as a child, how puzzled I was by the delay between my seeing the batsman striking the ball and my hearing it. We simply do not possess and cannot acquire omniscience.
Particular care needs to be taken when dealing with the self-professed unbiased, who include some of the most biased and intolerant people you will ever meet.
As a writer of fiction, you can only be true to yourself. If you try to fit your writing around somebody else’s prejudices, you are likely to render it insipid and bland at best. I remember one writer who contrived to render a story quite unintelligible by substituting ‘they’ and ‘their’ for every masculine or feminine pronoun. Which is fine if you want to be insipid or unintelligible, but otherwise not.
A writer in a dictatorship or living under a totalitarian regime may not have this choice, but I still believe a writer in the free world should be able to choose to go full speed ahead and damn the torpedoes!