Right, I think that people in this thread, and on /r/law generally, can be a little too quick to embrace the literacy of American legalism rather than thinking things through. Downthread just a bit, there's certainly an embrace of the idea that the court should not "make law" and that this is essentially such a preordained issue that it is an exemplar of "The CRA doesn't extend to cultural norms, so sucks to be you, petition your legislature" separation of powers that there hasn't been nearly as much thought put into the alternative.

A court could just as easily say that Title VII was clearly passed to remedy the widespread problem of racially discriminatory hiring, that the court continues to have jurisdiction because A) the CRA is still in effect, and B) the problem underlying both the CRA of 1964 and the five others passed before it, that of anti-African American racial prejudice, continues to be a problem today, that the "cultural norm/immutable characteristic" distinction cannot be tenable because it provides impermissibly large coverage to employers who would prefer not to hire African Americans (the original problem) but need a facially nondiscriminatory reason to do so. The court could then reasonably conclude that an employer's ban on dreadlocks, when it has no compelling reason to do so, will disproportionately burden African Americans, and therefore is unlawful even if we can't demonstrate anti-African American animus here, and that a finding to the contrary could simply result in all discriminatory employers adopting the (very thinly veiled) rhetoric of "cultural norms" to make their discrimination legal, which would not remedy the problem Title VII was intended to remedy.

Some on /r/law might prefer that courts defer to the literal words of the statute and none beyond, but the US doesn't have that kind of legal system to begin with, and the above reasoning - while a reasonable person could argue against it - isn't so beyond reason that it clearly implicates separation of powers, is unconstitutional, or is just fabricating law wholesale. Title VII really was intending to prohibit discrimination on the basis of race in the realm of employment. It probably is the case that a discriminatory employer can come up with "cultural" reasons for their actions literally all day long, especially if they can invoke "cultural norms" as a magic word to make Title VII go away. Courts, in the US, largely update their understanding of law as time passes, including statutory law, by their nature. The EEOC was not outside the realm of reasonable thought.

More philosophically, the US has a long, long history of "oh we're not being racist towards blacks we're just being facially neutral Xist" when, in fact, racism is being given cover; so much so that we should probably pause and seriously give consideration that we might be falling into that trap if the form of our decision largely looks like "this isn't racism towards blacks it's just facially racially neutral cultural bias against a thing blacks disproportionately do!" We might arrive there if we, rather than marveling at the beautiful consistency of the decision, more critically engaged with the role of the courts in American human rights jurisprudence, including its role before and between all the Civil Rights acts, particularly with respect to race which has a special place in American jurisprudence owing to the deep and complex ways that racial discrimination in the US has stained our history and become a part of our culture. I'll be radical and suggest that, maybe, given this history, the role of the courts should be to interpret human rights law broadly when there's a constitutional or statutory basis to do so and, if they get it wrong, then the legislature can step in to correct them, rather than construing human rights protections narrowly and hoping that the minority will have enough legislative clout to correct things. Nonetheless, I don't think you need to embrace such a radical position to see a potentially legal alternative ruling here.

Or we can legalistically read a distinction between "immutable" and "mutable" characteristics in our interpretation of the statute (which, for those of us preferring the civil law version of the US, is not a distinction made in the statute) and then downvote anything critical of the result for just not quite understanding the philosophy of American law well enough to realize this is obviously the correct decision and the impacted minority culture obviously just needs to use their certainly equal power to petition the legislature to correct the situation.

And hopefully an American legislature isn't doing something like trying to suppress the vote of that minority; that would really be awkward in this whole picture.