It was the 90s.. rules were different then ! I still have my white pants deep in the closet somewhere.. they haven't seen the light of day in a while though :)
I worked at Bell Labs back when this photo was taken - my office pretty much looked exactly like this, chair, furniture, Sun SPARCStation on the floor...
Bjarne still rocks white pants sometimes to this day though ! And the same haircut - he really committed to the look :)