The reason that sort of line is so at odds with reality is that the Court doesn't have the authority to entrench anything. It can only call out action that's at odds with democratically developed law.
The Supreme Court can't tell universities how to admit students. It can point out when their means of admission run afoul of law, but it can't dictate to them the way to act.
The quote here misrepresents the actual functioning of the Court in the US system of government, and that's its fatal flaw.