No, I think they meant that removing legacy admissions will result in fewer white guys getting admitted, but that’s ok.
That said, i support legacies because these private universities at just that--private institutions, and the first amendment gives you the right to associate with whom you wish.
I'm not a legacy admit (my admission was denied, the fools!) but my dad definitely imparted some of MIT's culture on me before I left for college.
https://law.justia.com/constitution/us/amendment-01/10-right...
There is generally considered rights held by (among other things) highly selective organizations to not have to follow public accommodation laws (which might harm their selectivity).
Professors of course contribute to the student culture too, but by no means as much as the students themselves.