Put yourself in Bernie’s shoes. The right is using cultural/identity issues to divide white working people from your woke activists. What do you do?
There are no good choices here. You could move to the right on culture war issues and increase the size of your voting pool, but you would lose your most fervent supporters, who represent the future of your movement. If you side with the wokes, you lose any hope of creating an effective majority in the country for the foreseeable future.
It appears to me that the decision has been made by default in favor of the activists. The future may belong to your movement, but for the present, you are stuck in the mud.