According to the Certified Information Security Manager (CISM) Study Manual, "The primary objective of information security governance is to provide a framework for managing and controlling information security practices and technologies at an enterprise level. Its goal is to manage and reduce risk through a process of identification, assessment, and management of those risks." While demonstrating senior management commitment, compliance with industry best practices, and ensuring user compliance with policies are all important aspects of information security governance, they are not the primary objective. The primary objective is to manage and reduce risk by establishing a framework for managing and controlling information security practices and technologies at an enterprise level.
Reference:
Certified Information Security Manager (CISM) Study Manual, 15th Edition, Page 60.

The best course of action for the information security manager to support the initiative of leveraging popular social network platforms to promote the organization's products and services is to assess the security risk associated with the use of social networks. Security risk assessment is a process of identifying, analyzing, and evaluating the potential threats and vulnerabilities that may affect the confidentiality, integrity, and availability of information assets and systems. By conducting a security risk assessment, the information security manager can provide valuable input to the decision-making process regarding the benefits and costs of using social networks, as well as the appropriate security controls and mitigation strategies to reduce the risk to an acceptable level. The other options are not the best course of action, although they may be part of the security risk management process. Establishing processes to publish content on social networks is an operational task that should be performed after assessing the security risk and implementing the necessary controls. Conducting vulnerability assessments on social network platforms is a technical activity that may not be feasible or effective, as the organization does not have control over the platforms' infrastructure and configuration. Developing security controls for the use of social networks is a preventive measure that should be based on the results of the security risk assessment and aligned with the organization's risk appetite and tolerance

Social engineering is a technique used by attackers to manipulate individuals into divulging sensitive information or performing actions that can compromise the security of an organization. Multi-factor authentication (MFA) is a security mechanism that requires users to provide at least two forms of authentication to verify their identity. By requiring MFA, even if an attacker successfully obtains a user's credentials through social engineering, they will not be able to access the network without the additional form of authentication.