The director of human resources investigated, discovered that the concerns which the nurses had raised were shared by many others and that, in fact, many of their complaints were valid. He then met with all of the employees, admitted that some of their complaints were valid but informed them that they were still supposed to support decisions made by management. Eventually, he met with the three nurses who had originally brought the complaints to his attention and determined that they would be unwilling to support the decisions of management. The Supreme Court determined that the National Labor Relations Act did not apply to these nurses because they supervised nurse's aides and the National Labor Relations Act does not apply to supervisors. The reason the NLRB developed its confusing and complex doctrine that sometimes supervisors are not supervisors, is because the nature of certain occupations requires that one employee supervise other employees.
Professionals are, by definition, persons with additional education and expertise.
In a nursing home, nurse's aides are untrained and rely on professional nurses for direction and problem solving on how to take care of patients and other matters. Congress was trying to create a distinction between management and labor. Management adopts certain rules which it expects its employees to obey. Supervisors are usually understood to be the people who determine the rules or see that they are enforced. The NLRB tried to articulate a distinction between supervision in the management sense and supervision in the sense that one employee, having superior education and experience, becomes a resource for other employees.