“The National Labor Relations Board has taken a deregulatory approach to labor and workplace law under the Trump administration, and the agency has largely stayed on that management-side course during the coronavirus pandemic. The outbreak has presented novel legal issues under the National Labor Relations Act, the central statute governing workers’ and businesses’ rights concerning unionization, which the NLRB is charged with enforcing, enmeshing it in disputes that can be hotly contested even when there’s no overarching crisis.”