Judicial Activism in Brown v Board of Education

This opinion on the WSJ questions the reasons behind Brown v the Board of Education. The case was determined based on "modern psychological knowledge", instead of reasons of policy.

Two questions:

a) If the judge had used some other "modern" fact and came to the opposite conclusion, would he have been derided as out-of-touch?

b) Is it possible for the court to make a decision of with policy elements without deciding what the correct outcome is, and then finding the reasons later?