I would see zero problem if Sanders did that. I simply disagree that every group in society needs to be perfectly representative of demographics at all time. Your focus is clearly not where it needs to be.
On a rarely talked about aspect of that issue, maybe there is a chance of synergy with people of similar cultures? On the flip side, maybe it leads to comfortability which can be negative. I don't actually know the answer here, but neither do you.
At the end of the day, society is trying to get rid itself of actual racism. And when you complain every time a group is not a direct representation of demographics, it honestly makes race relations worse. People start conflating actual racism with this type of micro management.