It could be. The only new component that HUSL defines is saturation (it's a distorted version of CIELCHuv's chroma). Both hue and lightness are exactly like CIE defined them after doing actual empirical research on color vision.
So while the hue component isn't perfectly perceptually uniform, there is no way I could improve it without doing an actual study.
So while the hue component isn't perfectly perceptually uniform, there is no way I could improve it without doing an actual study.