You actually have it backwards. Your claim is that legacy admissions bias in favor of the predominant race might be true for a school that had race-blind admittance criteria. In the opposite case, however, legacy admissions bias against people of the predominant race (for the general student).
Since legacy admissions come first, schools which practice affirmative action have a heavy bias against the predominant race (because those slots are all filled by legacy candidate). Which means that if you're of the predominant race, you have next to no chance to be accepted by these universities... (I mean, everyone has next to no chance, but for people of the predominant race, they are discriminated against severely).
In general, though, college admissions are pretty terrible... Having spoken with someone who worked in admissions at one of these universities, if you have a bright kid, you're better off moving to the middle of nowhere to make sure they're the valedictorian, rather than trying to send your kid to a great high school where why might only be salutatorian. Why? For smaller schools they rarely take more than one student from that school in any given year, so when the valedictorian who filled out applications to 10 top schools gets in to all 10? The salutatorian doesn't...
Since legacy admissions come first, schools which practice affirmative action have a heavy bias against the predominant race (because those slots are all filled by legacy candidate). Which means that if you're of the predominant race, you have next to no chance to be accepted by these universities... (I mean, everyone has next to no chance, but for people of the predominant race, they are discriminated against severely).
In general, though, college admissions are pretty terrible... Having spoken with someone who worked in admissions at one of these universities, if you have a bright kid, you're better off moving to the middle of nowhere to make sure they're the valedictorian, rather than trying to send your kid to a great high school where why might only be salutatorian. Why? For smaller schools they rarely take more than one student from that school in any given year, so when the valedictorian who filled out applications to 10 top schools gets in to all 10? The salutatorian doesn't...