According to the Professional in Business Analysis (PMI-PBA) Guide, stakeholder communication is the process of planning, managing, and monitoring the exchange of information among project stakeholders.
Stakeholder communication should be customized based on the stakeholders' needs, preferences, expectations, and level of involvement. In this scenario, the project manager should have customized stakeholder communications based on the key stakeholder's needs. This would have helped the project manager to keep the key stakeholder informed, engaged, and satisfied throughout the project, and to address any issues, concerns, or feedback that the key stakeholder may have. This would have also helped to avoid the situation where the key stakeholder rejected a feature deliverable due to lack of involvement or awareness.
Involved the key stakeholders in the decision-making process, analyzed the changes in stakeholder attributes, or documented the project vision and objectives are actions that should be taken as part of the stakeholder communication plan, not as a substitute for it. These actions do not address the root cause of the situation, which is the inadequate stakeholder communication. References: (Professional in Business Analysis Reference Materials source and documents)
* Professional in Business Analysis (PMI-PBA) Guide, Chapter 2, Section 2.4.1.1
* A Guide to the Project Management Body of Knowledge (PMBOK Guide) - Seventh Edition, Chapter 10, Section 10.2.2.1
* The Standard for Project Management - Seventh Edition, Chapter 3, Section 3.2.2.1