Positive discrimination is a clumsy phrase that merely adds fuel to the 'newly oppressed white male' theory bulls*** . Perhaps it should be re-defined as equalising opportunity, or an equality pathway, because the entire purpose of the principle is to render itself obsolete, by allowing disadvantaged groups greater access to opportunity than if social inequalites were seen as unimportant.
Of course, it shouldn't simply be defined by colour, nationality, gender or sexuality etc, but sometimes focus is required to just crowbar open the door enough to undermine some of the barriers that exist.
The whole point of it to get us to a place where what you are born as doesn't define your opportunities as much as it currently does. Should we be finding more ways to increase working class white people? Of course. And one of the best ways to do that is to diversify the gatekeepers and powerbrokers and decision makers. Because the same people who have both the desire and power to limit opportunities for minorities also have the same for the working class white man (unless he can be exploited).
Frankly we need an intersectional approach with individually tweaked elements. The whole 'downtrodden white man' thing is a lie sold to less advantaged white people by those in power, to keep them from realising who is actually screwing them and how - its the same playbook as the historical persecution of Jews, just with different detail.
More diversity in postions of influence benefits all but those who already have power and cling onto it like dragons guarding their hoards, which is a tiny percentage. Every meaningful study on the subject concludes this