In a situation such as that one, the judge is sometimes going to err in favor of the defendant and let the jury decide if there is probative value to the comment. The prosecution was the opportunity to point out (a) how old the comments were; (b) the circumstances in which they were made; and (c) Fuhrman's relationship with black officers. I don't remember enough of the specifics, nor know enough California law, to know how I would have ruled. How I 'feel' about it matters only within the scope of what California law says.
I heard a judge say that Ito should have declared a mistrial as soon as that testimony was made.
I thought Ito had ruled in camera that the comment was admissible, but it's been a long time. Again, it depends on whether Ito thought Simpson, as a defendant, should be given the opportunity to prevent the defense with the jury allowed to consider (a), (b), and (c). He may not have allowed the comment had it been introduced by the prosecution to discredit a defense witness. Things aren't perfectly even in the courtroom.
The question was obviously intended to bias a mostly Black jury. I will say Furhman should have said “I am sure I, like virtually every other person has used that word before, in fact you just used it yourself.”