Great post, but since when do Imperials have unnatural hair colours? 😐
Not hair colours specifically, but the Ralph McQuarrie art book (and I’m sure other sources) discuss how Lucas, right from the beginning, directed the artists in this way. The intention was that Imperials would use an unnatural colour scheme - black, white, grey, red - whereas rebels would use natural colours - browns, forest green, sky blue. There are exceptions but those guidelines were definitely given and broadly applied. So objecting to Holdo’s hair colour on that basis would be valid (though I think caring about that is a waste of a perfectly good care).
I for one can definitely imagine an Imperial (even in senior uniform) with pink hair looking pretty appropriate.