Serious misconduct as ground for dismissal practice question

Delta Precision Manufacturing, Inc. employed Mr. Benito Cruz as a Senior Engineer. In July 2022, Mr. Cruz sent an email to all employees expressing sympathy for a suspended manager and criticizing a third-party contractor, but did not insult or accuse the company or its officers. Delta terminated Mr. Cruz for serious misconduct, alleging that the email violated company confidentiality and undermined management authority. Mr. Cruz contests his dismissal. Was Mr. Cruz validly dismissed for serious misconduct? Explain.