That said...
You're missing that some problems are, actually, entirely perceptive. You're right that changing the mirror to hide problems isn't addressing the underlying issue, but sometimes treatment of symptoms is the only available (or possible the most effective) option. Like everything else, it's one tool that can be applied poorly or effectively.
> it would be unfair to simply damage the service for one group to appease the another
This is ineffective as a stand-alone principle. The failure mode is described as "your freedom ends where mine begins" and is clearly visible in the exaggerated (and somewhat contrived) example of "damaging services for murdering to appease those who want to remain un-murdered is good".
Like all principles, this has both extreme-case failure modes (services for murderers) but also fuzzy-case failure modes. If the term for my identity is sexualized, when that identity has nothing to do with sexuality... well, what's fair? Why should group X define the term instead of group Y?
So, for cases where the problem is primarily perceptive (or the symptoms are primarily perceptive), seems reasonable to me to warp the mirror. It's like using glasses: you're already looking through a warped lens, so use a correspondingly warped lens to correct.
My actual point is that systems that incidentally encode biases then let you better examine those biases, and, depending on the situation, do stuff to address them.
After your proposed changes it is no longer visible, and we can no longer make informed choices - people searching for "black girls" still want the same thing, but they're getting a worse service (results that don't fit their intent) just to hide them and their preferences from other parts of the society. There's also a feedback loop in the opposite direction, if there are real problems that simply are hidden, they're not going to get fixed.
On the other hand, it's worth examining the actual problem - it's worth noting that people who do want to find sexual pictures of black girls are just as valid users as black girls, and any fair solution must keep both of their preferences in mind; it would be unfair to simply damage the service for one group to appease the another. IMHO a fair solution would be based on data about what the people who use that query actually want (in some equivalence to picking equal opportunities in the "equal opportunities vs equal outcomes" tradeoff dilemma) - if some people are using the term in their daily search and some are not, then the interests of these frequent users could reasonably be considered more important. Aggressive personalization (different users having wildly different search results for the same term because of the differences in the assumed intent) is another way to do that, but it brings a bunch of other problems.