Many specific racist behaviors are of course either sometimes or always illegal, but those concepts are individually known to the law, not outlawed as racism per se.
What's more, the ruling you linked did not address the kind of quotas which the FANG company was discussing in the quoted email. The university was setting aside a certain percentage of the total and rejecting white people who might otherwise have qualified to keep room for racial minorities, which was key to the ruling. The FANG company was evaluating white people just as it would have done without the quotas, but it was simply allowing extra hiring of racial minorities beyond the normal budgets until certain targets/quotas were met. Whether this is legal or not is out of scope of that ruling. (Maybe other rulings have addressed this; I'm not sure.)
I'm aware of the specificity of the ruling but the basis on which the ruling was made is much more general. Depending on the entity different laws would be in question; a fully private entity would probably be violating the civil rights act of 1964, while in the case of university admissions and funding the current systems are still in violation of the equal protection clause. Interpretations of the civil rights act of 1964 that advantage groups for no reason other than race are also unconstitutional.
Note this is a lot different than allowing race to be a factor of a multifaceted evaluation -- it's inappropriate to have race at all be part of the evaluation. Instead substitute it for socioeconomic background.
I'm not sure yet how to fully clarify this, so consider the Missouri government's statutory commitment to spend X% of the budget with women or minority owned businesses. In a degenerate case this means e.g. even the most unqualified candidate could be awarded a contract solely on the basis of race, violating the equal protection clause.
(Practically this expenditure law means larger companies have "independent" women and minority owned businesses as subcontractors who might contract the work back to a business owned by the larger company that can do the work.)
My understanding of the state of the law is that race is currently allowed to be considered as a factor in university admissions if available workable race-neutral alternatives do not suffice, and that (as of 2016) the University of Texas at Austin's policy of using race as such a factor was found to be constitutional for this reason.
More reading on that: https://en.wikipedia.org/wiki/Fisher_v._University_of_Texas_...
The viability of this precedent is highly uncertain since it was a 4-3 ruling (one SCOTUS seat vacant at the time and one justice recused), and since its majority was four of the liberal justices of whom one (the late RBG) has now been replaced by the conservative Justice Barrett. But it hasn't yet been overruled, and it was a SCOTUS majority ruling and not dicta, so it's likely to be followed by lower courts unless and until it's overruled by SCOTUS.
Questions of being inappropriate are, of course, a personal opinion-based judgment call and not a question of legality.
